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1

Density Functional Theory for Superconductors  

E-Print Network [OSTI]

Density Functional Theory for Superconductors LATHIOTAKIS, A. MARQUES, 1,2,3 LU DERS, L. FAST, 2004 words: theory superconductors; density functional theory; critical temperature; exchange matter physics theoretical chemistry is density functional theory (DFT). foundations were established mid

Gross, E.K.U.

2

Density Functional Theory for Superconductors  

E-Print Network [OSTI]

Density Functional Theory for Superconductors N. N. LATHIOTAKIS,1,2 M. A. L. MARQUES,1,2,3 M. LU; density functional theory; critical temperature; exchange and correlation; phonon and theoretical chemistry is density functional theory (DFT). Its foundations were established in the mid-1960s

Gross, E.K.U.

3

Density Functional Theory (DFT) Simulated Annealing (SA)  

E-Print Network [OSTI]

. . . . . . . . 9 2009 #12;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory) % Lattice-Boltzmann (LBM) #12;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory (DFT;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory (DFT) Simulated Annealing (SA) Monte Carlo &$ ' ' (GCMC

4

Time Dependent Density Functional Theory An introduction  

E-Print Network [OSTI]

Time Dependent Density Functional Theory An introduction Francesco Sottile LSI, Ecole Polytechnique (ETSF) Time Dependent Density Functional Theory Palaiseau, 7 February 2012 1 / 32 #12;Outline 1 Frontiers 4 Perspectives and Resources Francesco Sottile (ETSF) Time Dependent Density Functional Theory

Botti, Silvana

5

Time Dependent Density Functional Theory An Introduction  

E-Print Network [OSTI]

Time Dependent Density Functional Theory An Introduction Francesco Sottile Laboratoire des Solides) Belfast, 29 Jun 2007 Time Dependent Density Functional Theory Francesco Sottile #12;Intro Formalism Dependent Density Functional Theory Francesco Sottile #12;Intro Formalism Results Resources Outline 1

Botti, Silvana

6

Jacek Dobaczewski Density functional theory and energy  

E-Print Network [OSTI]

Jacek Dobaczewski Density functional theory and energy density functionals in nuclear physics Jacek Functional #12;Jacek Dobaczewski Mean-Field Theory Density Functional Theory · mean-field one? Density Functional Theory: A variational method that uses observables as variational parameters. #12;Jacek

Dobaczewski, Jacek

7

Density functional theory George F. Bertsch  

E-Print Network [OSTI]

Density functional theory George F. Bertsch #3; Institute for Nuclear Theory and Department of Physics University of Tsukuba Tsukuba 305-8577 Japan Abstract Density functional theory is a remarkably Time-dependent density functional theory: the equations 34 A Optical properties

Bertsch George F.

8

Combining Density Functional Theory and Density Matrix Functional Theory Daniel R. Rohr1  

E-Print Network [OSTI]

Combining Density Functional Theory and Density Matrix Functional Theory Daniel R. Rohr1 , Julien and CNRS, 4 place Jussieu, 75252 Paris, France We combine density-functional theory with density cleavage is an ubiquitous process for chemistry. Density-matrix functional theory (DMFT) (see, e.g., Refs

Paris-Sud XI, Université de

9

Density Functional Theory Models for Radiation Damage  

E-Print Network [OSTI]

Density Functional Theory Models for Radiation Damage S.L. Dudarev EURATOM/CCFE Fusion Association, DFT Abstract Density functional theory models developed over the past decade provide unique phenomena. Density functional theory models have effectively created a new paradigm for the scientific

10

Time Dependent Density Functional Theory An introduction  

E-Print Network [OSTI]

Time Dependent Density Functional Theory An introduction Francesco Sottile LSI, Ecole Polytechnique) Time Dependent Density Functional Theory Palaiseau, 26 May 2014 1 / 62 #12;Outline 1 Introduction: why and Resources Francesco Sottile (ETSF) Time Dependent Density Functional Theory Palaiseau, 26 May 2014 2 / 62

Botti, Silvana

11

DENSITY FUNCTIONAL THEORY, THE MODERN TREATMENT OF  

E-Print Network [OSTI]

DENSITY FUNCTIONAL THEORY, THE MODERN TREATMENT OF ELECTRON CORRELATIONS E.K.U. Gross and Stefan The basic idea of density functional theory is to describe a many-electron system exclusively and completely-consistent scheme, known as the Kohn-Sham scheme [2], is the heart of modern density functional theory

Gross, E.K.U.

12

Open problems in nuclear density functional theory  

E-Print Network [OSTI]

This note describes five subjects of some interest for the density functional theory in nuclear physics. These are, respectively, i) the need for concave functionals, ii) the nature of the Kohn-Sham potential for the radial density theory, iii) a proper implementation of a density functional for an "intrinsic" rotational density, iv) the possible existence of a potential driving the square root of the density, and v) the existence of many models where a density functional can be explicitly constructed.

B. G. Giraud

2009-11-30T23:59:59.000Z

13

KH Computational Physics-2009 Density Functional Theory (DFT) Density Functional Theory  

E-Print Network [OSTI]

KH Computational Physics- 2009 Density Functional Theory (DFT) Density Functional Theory of interacting particles. Kristjan Haule, 2009 ­2­ #12;KH Computational Physics- 2009 Density Functional Theory functional of n. Kristjan Haule, 2009 ­3­ #12;KH Computational Physics- 2009 Density Functional Theory (DFT

Haule, Kristjan

14

Density functional theory of electrowetting  

E-Print Network [OSTI]

The phenomenon of electrowetting, i.e., the dependence of the macroscopic contact angle of a fluid on the electrostatic potential of the substrate, is analyzed in terms of the density functional theory of wetting. It is shown that electrowetting is not an electrocapillarity effect, i.e., it cannot be consistently understood in terms of the variation of the substrate-fluid interfacial tension with the electrostatic substrate potential, but it is related to the depth of the effective interface potential. The key feature, which has been overlooked so far and which occurs naturally in the density functional approach is the structural change of a fluid if it is brought into contact with another fluid. These structural changes occur in the present context as the formation of finite films of one fluid phase in between the substrate and the bulk of the other fluid phase. The non-vanishing Donnan potentials (Galvani potential differences) across such film-bulk fluid interfaces, which generically occur due to an unequal partitioning of ions as a result of differences of solubility contrasts, lead to correction terms in the electrowetting equation, which become relevant for sufficiently small substrate potentials. Whereas the present density functional approach confirms the commonly used electrocapillarity-based electrowetting equation as a good approximation for the cases of metallic electrodes or electrodes coated with a hydrophobic dielectric in contact with an electrolyte solution and an ion-free oil, a significantly reduced tendency for electrowetting is predicted for electrodes coated with a dielectric which is hydrophilic or which is in contact with two immiscible electrolyte solutions.

Markus Bier; Ingrid Ibagon

2014-02-10T23:59:59.000Z

15

DENSITY FUNCTIONAL THEORY OF FIELD THEORETICAL SYSTEMS  

E-Print Network [OSTI]

DENSITY FUNCTIONAL THEORY OF FIELD THEORETICAL SYSTEMS E. Engel Inst. fur Theor. Physik background of relativistic density functional theory is emphasized and its consequences for relativistic Kohn-Sham equations are shown. The local density approximation for the exchange energy functional is reviewed

Engel, Eberhard

16

Density Functional Theory (DFT) Rob Parrish  

E-Print Network [OSTI]

Density Functional Theory (DFT) Rob Parrish robparrish@gmail.com 1 #12;Agenda · The mechanism Easy to do this Why? Because of Hermitian Operators: Kinetic Energy Density: #12;Density Functional The density completely defines the observable state of the system: The way in which it does so (the functional

Sherrill, David

17

Pair densities in density functional theory  

E-Print Network [OSTI]

The exact interaction energy of a many-electron system is determined by the electron pair density, which is not well-approximated in standard Kohn-Sham density functional models. Here we study the (complicated but well-defined) exact universal map from density to pair density. We show that many common functionals, including the most basic version of the LDA (Dirac exchange with no correlation contribution), arise from particular approximations of this map. We develop an algorithm to compute the map numerically, and apply it to one-parameter families {a*rho(a*x)} of one-dimensional homogeneous and inhomogeneous single-particle densities. We observe that the pair density develops remarkable multiscale patterns which strongly depend on both the particle number and the "width" 1/a of the single-particle density. The simulation results are confirmed by rigorous asymptotic results in the limiting regimes a>>1 and a<<1. For one-dimensional homogeneous systems, we show that the whole spectrum of patterns is rep...

Chen, Huajie

2015-01-01T23:59:59.000Z

18

Quantum critical benchmark for density functional theory  

E-Print Network [OSTI]

Two electrons at the threshold of ionization represent a severe test case for electronic structure theory. A pseudospectral method yields a very accurate density of the two-electron ion with nuclear charge close to the critical value. Highly accurate energy components and potentials of Kohn-Sham density functional theory are given, as well as a useful parametrization of the critical density. The challenges for density functional approximations and the strength of correlation are also discussed.

Paul E. Grabowski; Kieron Burke

2014-08-09T23:59:59.000Z

19

HIGHLIGHT OF THE MONTH Orbital Functionals in Density Functional Theory  

E-Print Network [OSTI]

HIGHLIGHT OF THE MONTH Orbital Functionals in Density Functional Theory: The Optimized E#11;ectiveurzburg, Am Hubland, D-97074 Wurzburg, Germany The success of density functional theory hinges the development of modern density functional theory. In present-day language, the exact OEP should be called

Gross, E.K.U.

20

Modern applications of covariant density functional theory  

E-Print Network [OSTI]

Modern applications of Covariant Density Functional Theory (CDFT) are discussed. First we show a systematic investigation of fission barriers in actinide nuclei within constraint relativistic mean field theory allowing for triaxial deformations. In the second part we discuss a microscopic theory of quantum phase transitions (QPT) based on the relativistic generator coordinate method.

P. Ring; H. Abusara; A. V. Afanasjev; G. A. Lalazissis; T. Niksic; D. Vretenar

2011-09-19T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Magnetic fields and density functional theory  

SciTech Connect (OSTI)

A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.

Salsbury Jr., Freddie

1999-02-01T23:59:59.000Z

22

Density functional theory for carbon dioxide crystal  

SciTech Connect (OSTI)

We present a density functional approach to describe the solid?liquid phase transition, interfacial and crystal structure, and properties of polyatomic CO{sub 2}. Unlike previous phase field crystal model or density functional theory, which are derived from the second order direct correlation function, the present density functional approach is based on the fundamental measure theory for hard-sphere repulsion in solid. More importantly, the contributions of enthalpic interactions due to the dispersive attractions and of entropic interactions arising from the molecular architecture are integrated in the density functional model. Using the theoretical model, the predicted liquid and solid densities of CO{sub 2} at equilibrium triple point are in good agreement with the experimental values. Based on the structure of crystal-liquid interfaces in different planes, the corresponding interfacial tensions are predicted. Their respective accuracies need to be tested.

Chang, Yiwen; Mi, Jianguo, E-mail: mijg@mail.buct.edu.cn; Zhong, Chongli [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)

2014-05-28T23:59:59.000Z

23

Density Functional Theory Approach to Nuclear Fission  

E-Print Network [OSTI]

The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.

N. Schunck

2013-01-20T23:59:59.000Z

24

Time Dependent Density Functional Theory Application to Extended Systems  

E-Print Network [OSTI]

Time Dependent Density Functional Theory Application to Extended Systems Francesco Sottile Facility (ETSF) Donostia, 25 July 2007 Time Dependent Density Functional Theory Francesco Sottile #12 Density Functional Theory Francesco Sottile #12;Linear Periodic systems ALDA The Quest for the Holy

Botti, Silvana

25

Error Analysis in Nuclear Density Functional Theory  

E-Print Network [OSTI]

Nuclear density functional theory (DFT) is the only microscopic, global approach to the structure of atomic nuclei. It is used in numerous applications, from determining the limits of stability to gaining a deep understanding of the formation of elements in the universe or the mechanisms that power stars and reactors. The predictive power of the theory depends on the amount of physics embedded in the energy density functional as well as on efficient ways to determine a small number of free parameters and solve the DFT equations. In this article, we discuss the various sources of uncertainties and errors encountered in DFT and possible methods to quantify these uncertainties in a rigorous manner.

Nicolas Schunck; Jordan D. McDonnell; Jason Sarich; Stefan M. Wild; Dave Higdon

2014-07-11T23:59:59.000Z

26

Master's Thesis Density Functional Theory for  

E-Print Network [OSTI]

of the information found during my work. v #12;vi #12;Contents Abstract #12;Abstract This thesis presents a number of results for basic quantum mechanical models intended to be used in the development of density functional theory for systems with edges. Following previous work

Armiento, Rickard

27

DENSITY FUNCTIONAL THEORY OF NORMAL AND SUPERCONDUCTING ELECTRON LIQUIDS: EXPLICIT  

E-Print Network [OSTI]

DENSITY FUNCTIONAL THEORY OF NORMAL AND SUPERCONDUCTING ELECTRON LIQUIDS: EXPLICIT FUNCTIONALS VIA?th University Nathan, Queensland 4111, Australia Abstract The basic idea of density functional theory is to map potential which is a functional of the density. The central task of density functional theory is to #12;nd

Gross, E.K.U.

28

ORBITAL-FREE KINETIC-ENERGY DENSITY FUNCTIONAL THEORY  

E-Print Network [OSTI]

Chapter 5 ORBITAL-FREE KINETIC-ENERGY DENSITY FUNCTIONAL THEORY Yan Alexander Wang and Emily A Theory (DFT), there was the Thomas-Fermi (TF) model, which uses the electron density ¢¡ r£ (a function-dependent DFT Density-Functional Theory DI density-independent DM1 first-order reduced density matrix EDF energy

Wang, Yan Alexander

29

Density Functional Theory applied to the solid state...  

E-Print Network [OSTI]

Density Functional Theory applied to the solid state... An introduction to VASP Jeremie Zaffran 2nd Marom (PhD) #12;Contents I- DFT and its functionals A. On the density functional theory... B #12;I- DFT and its functionals #12;I-DFT and its functionals A- On the density functional theory Why

Adler, Joan

30

Periodic subsystem density-functional theory  

SciTech Connect (OSTI)

By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of KohnSham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline solids have been outside the applicability of FDE, mostly because of the lack of a periodic FDE implementation. To fill this gap, in this work we aim at extending FDE to treat subsystems of molecular and periodic character. This goal is achieved by a dual approach. On one side, the development of a theoretical framework for periodic subsystem DFT. On the other, the realization of the method into a parallel computer code. We find that periodic FDE is capable of reproducing total electron densities and (to a lesser extent) also interaction energies of molecular systems weakly interacting with metallic surfaces. In the pilot calculations considered, we find that FDE fails in those cases where there is appreciable density overlap between the subsystems. Conversely, we find FDE to be in semiquantitative agreement with KohnSham DFT when the inter-subsystem density overlap is low. We also conclude that to make FDE a suitable method for describing molecular adsorption at surfaces, kinetic energy density functionals that go beyond the GGA level must be employed.

Genova, Alessandro; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); Ceresoli, Davide [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); CNR-ISTM, Institute of Molecular Sciences and Technologies, Milano (Italy)

2014-11-07T23:59:59.000Z

31

Electronic excitations in complex systems: beyond density functional theory  

E-Print Network [OSTI]

Electronic excitations in complex systems: beyond density functional theory for real materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3 Time-dependent density functional theory 19 3.1 The Runge-Gross theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Model kernels from many-body perturbation theory 29 4.1 Time-dependent density functional theory

Botti, Silvana

32

Benchmark density functional theory calculations for nanoscale conductance  

E-Print Network [OSTI]

Benchmark density functional theory calculations for nanoscale conductance M. Strange,a I. S. The transmission functions are calculated using two different density functional theory methods, namely state density functional theory DFT . The resulting NEGF- DFT formalism provides a numerically efficient

Thygesen, Kristian

33

THE MANY-ELECTRON ENERGY IN DENSITY FUNCTIONAL THEORY  

E-Print Network [OSTI]

THE MANY-ELECTRON ENERGY IN DENSITY FUNCTIONAL THEORY From Exchange-Correlation Functional Design to the configuration of its electrons. Computer programs based on density functional theory (DFT) can calculate applicable within the field of computational density functional theory. Sammanfattning Att förutsäga

Armiento, Rickard

34

Symmetry energy in nuclear density functional theory  

E-Print Network [OSTI]

The nuclear symmetry energy represents a response to the neutron-proton asymmetry. In this survey we discuss various aspects of symmetry energy in the framework of nuclear density functional theory, considering both non-relativistic and relativistic self-consistent mean-field realizations side-by-side. Key observables pertaining to bulk nucleonic matter and finite nuclei are reviewed. Constraints on the symmetry energy and correlations between observables and symmetry-energy parameters, using statistical covariance analysis, are investigated. Perspectives for future work are outlined in the context of ongoing experimental efforts.

W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar

2013-07-22T23:59:59.000Z

35

Orbital-optimized density cumulant functional theory  

SciTech Connect (OSTI)

In density cumulant functional theory (DCFT) the electronic energy is evaluated from the one-particle density matrix and two-particle density cumulant, circumventing the computation of the wavefunction. To achieve this, the one-particle density matrix is decomposed exactly into the mean-field (idempotent) and correlation components. While the latter can be entirely derived from the density cumulant, the former must be obtained by choosing a specific set of orbitals. In the original DCFT formulation [W. Kutzelnigg, J. Chem. Phys. 125, 171101 (2006)] the orbitals were determined by diagonalizing the effective Fock operator, which introduces partial orbital relaxation. Here we present a new orbital-optimized formulation of DCFT where the energy is variationally minimized with respect to orbital rotations. This introduces important energy contributions and significantly improves the description of the dynamic correlation. In addition, it greatly simplifies the computation of analytic gradients, for which expressions are also presented. We offer a perturbative analysis of the new orbital stationarity conditions and benchmark their performance for a variety of chemical systems.

Sokolov, Alexander Yu., E-mail: asokolov@uga.edu; Schaefer, Henry F. [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)] [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)

2013-11-28T23:59:59.000Z

36

A Guided Tour of TimeDependent Density Functional Theory  

E-Print Network [OSTI]

A Guided Tour of Time­Dependent Density Functional Theory Kieron Burke 1 and E.K.U. Gross 2 1 outlook. 1 Introduction and User's Guide Density functional theory is the study of the one in density functional theory, driven largely by its applications in quantum chemistry[3]. This is due

Gross, E.K.U.

37

EFFECTIVE MAXWELL EQUATIONS FROM TIME-DEPENDENT DENSITY FUNCTIONAL THEORY  

E-Print Network [OSTI]

EFFECTIVE MAXWELL EQUATIONS FROM TIME-DEPENDENT DENSITY FUNCTIONAL THEORY WEINAN E, JIANFENG LU and magnetic fields are derived starting from time-dependent density functional theory. Effective permittivity with the density functional theory [2­4] instead of the many-body Schr¨odinger or Dirac equations. This is because

Bigelow, Stephen

38

Time Dependent Density Functional Theory Applications, limitations and ... new frontiers  

E-Print Network [OSTI]

Time Dependent Density Functional Theory Applications, limitations and ... new frontiers Francesco Spectroscopy Facility (ETSF) Vienna, 19 January 2007 1/55 Time Dependent Density Functional Theory Francesco Sottile #12;Time-Dependent Density Functional Theory Applications and results: The ETSF Outline 1 Time

Botti, Silvana

39

RELATIVISTIC DENSITY FUNCTIONAL THEORY: FOUNDATIONS AND BASIC FORMALISM  

E-Print Network [OSTI]

1 Chapter 10 RELATIVISTIC DENSITY FUNCTIONAL THEORY: FOUNDATIONS AND BASIC FORMALISM E. Engela a An overview of relativistic density functional theory (RDFT) is presented with special emphasis on its field-Cluster schemes in recent years density functional theory (DFT) still represents the method of choice

Engel, Eberhard

40

Covariant density functional theory for antimagnetic rotation  

E-Print Network [OSTI]

Following the previous letter on the first microscopic description of the antimagnetic rotation (AMR) in 105Cd, a systematic investigation and detailed analysis for the AMR band in the frame-work of tilted axis cranking (TAC) model based on covariant density functional theory are carried out. After performing the microscopic and self-consistentTAC calculations with an given density functional, the configuration for the observed AMR band in 105Cd is obtained from the single-particle Routhians. With the configuration thus obtained, the tilt angle for a given rotational frequency is determined self-consistently by minimizing the total Routhian with respect to the tilt angle. In such a way, the energy spectrum, total angular momenta, kinetic and dynamic moments of inertia, and the B(E2) values for the AMR band in 105Cd are calculated. Good agreement with the data is found. By investigating microscopically the contributions from neutrons and protons to the total angular momentum, the "two-shears-like" mechanism in the AMR band is clearly illus-trated. Finally, the currents leading to time-odd mean fields in the Dirac equation are presented and discussed in detail. It is found that they are essentially determined by the valence particles and/or holes. Their spatial distribution and size depend onthe specific single-particle orbitals and the rotational frequency.

P. W. Zhao; J. Peng; H. Z. Liang; P. Ring; J. Meng

2012-05-04T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Some challenges for Nuclear Density Functional Theory  

E-Print Network [OSTI]

We discuss some of the challenges that the DFT community faces in its quest for the truly universal energy density functional applicable over the entire nuclear chart.

T. Duguet; K. Bennaceur; T. Lesinski; J. Meyer

2006-06-20T23:59:59.000Z

42

1 Density Functional Theory for Emergents Robert O. Jones  

E-Print Network [OSTI]

1 Density Functional Theory for Emergents Robert O. Jones Peter-Gr¨unberg-Institut PGI-1 and German the widespread use of density functional (DF) theory in materials science and chemistry and the physical insight as basic variable 3 3 An "approximate practical method" 5 4 Density functional formalism 7 4.1 Single

43

Particle-Number Projection and the Density Functional Theory  

E-Print Network [OSTI]

In the framework of the Density Functional Theory for superconductors, we study the restoration of the particle number symmetry by means of the projection technique. Conceptual problems are outlined and numerical difficulties are discussed. Both are related to the fact that neither the many-body Hamiltonian nor the wave function of the system appear explicitly in the Density Functional Theory. Similar obstacles are encountered in self-consistent theories utilizing density-dependent effective interactions.

J. Dobaczewski; M. V. Stoitsov; W. Nazarewicz; P. -G. Reinhard

2007-08-03T23:59:59.000Z

44

Density-functional theory of nonuniform classical liquids: An extended modified weighted-density approximation  

E-Print Network [OSTI]

Density-functional theory of nonuniform classical liquids: An extended modified weighted-density the approximationstreat long-rangeand short-rangepotentials. I. INTRODUCTION The density-functional theory of nonuniform of density- functional theory to the problem of freezing of classical liquids,4 and in particular

Likos, Christos N.

45

Density Functional Theory Study of Oxygen Reduction Activity...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes. Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes. Abstract: The...

46

Density and pair-density scaling for deriving the Euler equation in density-functional and pair-density-functional theory  

SciTech Connect (OSTI)

A link between density and pair density functional theories is presented. Density and pair density scaling are used to derive the Euler equation in both theories. Density scaling provides a constructive way of obtaining approximations for the Pauli potential. The Pauli potential (energy) of the density functional theory is expressed as the difference of the scaled and original exchange-correlation potentials (energies).

Nagy, A. [Department of Theoretical Physics, University of Debrecen, H-4010 Debrecen (Hungary)

2011-09-15T23:59:59.000Z

47

Gedanken densities and exact constraints in density functional theory  

SciTech Connect (OSTI)

Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is not an approximation to it. We further derive a strongly and optimally tightened bound on the exchange enhancement factor of a two-electron density, which is satisfied by the local density approximation but is violated by all published GGA's or meta-GGAs. Finally, some consequences of the non-uniform density-scaling behavior for the asymptotics of the exchange enhancement factor of a GGA or meta-GGA are given.

Perdew, John P. [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States) [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States); Ruzsinszky, Adrienn; Sun, Jianwei [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States)] [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Burke, Kieron [Department of Chemistry and Department of Physics, University of California, Irvine, California 92697 (United States)] [Department of Chemistry and Department of Physics, University of California, Irvine, California 92697 (United States)

2014-05-14T23:59:59.000Z

48

Constrained Density-Functional Theory--Configuration Interaction  

E-Print Network [OSTI]

In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density ...

Kaduk, Benjamin James

2012-01-01T23:59:59.000Z

49

Dynamical density functional theory for colloidal particles with arbitrary shape  

E-Print Network [OSTI]

Starting from the many-particle Smoluchowski equation, we derive dynamical density functional theory for Brownian particles with an arbitrary shape. Both passive and active (self-propelled) particles are considered. The resulting theory constitutes a microscopic framework to explore the collective dynamical behavior of biaxial particles in nonequilibrium. For spherical and uniaxial particles, earlier derived dynamical density functional theories are recovered as special cases. Our study is motivated by recent experimental progress in preparing colloidal particles with many different biaxial shapes.

Raphael Wittkowski; Hartmut Lwen

2011-06-12T23:59:59.000Z

50

Functional designed to include surface effects in self-consistent density functional theory R. Armiento1,  

E-Print Network [OSTI]

Functional designed to include surface effects in self-consistent density functional theory R 2005 We design a density-functional-theory DFT exchange-correlation functional that enables an accurate density functional theory1 DFT is a method for electronic structure calculations of unparalleled

Armiento, Rickard

51

Magnetic fields and density functional theory  

E-Print Network [OSTI]

development of the general theory, Grayce and Harris used an electron gas approach to obtain a local energy

Jr, F.-Salsbury

2010-01-01T23:59:59.000Z

52

Preface: Special Topic on Advances in Density Functional Theory  

SciTech Connect (OSTI)

This Special Topic Issue on the Advances in Density Functional Theory, published as a celebration of the fifty years of density functional theory, contains a retrospective article, a perspective article, and a collection of original research articles that showcase recent theoretical advances in the field. It provides a timely discussion reflecting a cross section of our understanding, and the theoretical and computational developments, which have significant implications in broad areas of sciences and engineering.

Yang, Weitao [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)] [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)

2014-05-14T23:59:59.000Z

53

Density Functional Theory with Dissipation: Transport through Single Molecules  

SciTech Connect (OSTI)

A huge amount of fundamental research was performed on this grant. Most of it focussed on fundamental issues of electronic structure calculations of transport through single molecules, using density functional theory. Achievements were: (1) First density functional theory with dissipation; (2) Pseudopotential plane wave calculations with master equation; (3) Weak bias limit; (4) Long-chain conductance; and (5) Self-interaction effects in tunneling.

Kieron Burke

2012-04-30T23:59:59.000Z

54

Molecular Binding Energies from Partition Density Functional Theory  

SciTech Connect (OSTI)

Approximate molecular calculations via standard Kohn-Sham density functional theory are exactly reproduced by performing self-consistent calculations on isolated fragments via partition density functional theory [P. Elliott, K. Burke, M. H. Cohen, and A. Wasserman, Phys. Rev. A 82, 024501 (2010)]. We illustrate this with the binding curves of small diatomic molecules. We find that partition energies are in all cases qualitatively similar and numerically close to actual binding energies. We discuss qualitative features of the associated partition potentials.

Nafziger, J.; Wu, Q.; Wasserman, A.

2011-12-21T23:59:59.000Z

55

The problem of the universal density functional and the density matrix functional theory  

SciTech Connect (OSTI)

The analysis in this paper shows that the Hohenberg-Kohn theorem is the constellation of two statements: (i) the mathematically rigorous Hohenberg-Kohn lemma, which demonstrates that the same ground-state density cannot correspond to two different potentials of an external field, and (ii) the hypothesis of the existence of the universal density functional. Based on the obtained explicit expression for the nonrel-ativistic particle energy in a local external field, we prove that the energy of the system of more than two non-interacting electrons cannot be a functional of the inhomogeneous density. This result is generalized to the system of interacting electrons. It means that the Hohenberg-Kohn lemma cannot provide justification of the universal density functional for fermions. At the same time, statements of the density functional theory remain valid when considering any number of noninteracting ground-state bosons due to the Bose condensation effect. In the framework of the density matrix functional theory, the hypothesis of the existence of the universal density matrix functional corresponds to the cases of noninteracting particles and to interaction in the Hartree-Fock approximation.

Bobrov, V. B., E-mail: vic5907@mail.ru; Trigger, S. A., E-mail: satron@mail.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2013-04-15T23:59:59.000Z

56

Scaled Density Functional Theory Correlation Functionals Mohammed M. Ghouri,a  

E-Print Network [OSTI]

Scaled Density Functional Theory Correlation Functionals Mohammed M. Ghouri,a Saurabh Singh,a and B by Density Functional Theory (DFT)2 correlation functionals without significant deterioration that a simple one parameter scaling of the dynamical correlation energy estimated by the Density Functional

Ramachandran, Bala (Ramu)

57

Time-dependent density-functional theory for open systems  

E-Print Network [OSTI]

By introducing the self-energy density functionals for the dissipative interactions between the reduced system and its environment, we develop a time-dependent density-functional theory formalism based on an equation of motion for the Kohn-Sham reduced single-electron density matrix of the reduced system. Two approximate schemes are proposed for the self-energy density functionals, the complete second order approximation and the wide-band limit approximation. A numerical method based on the wide-band limit approximation is subsequently developed and implemented to simulate the steady and transient current through various realistic molecular devices. Simulation results are presented and discussed.

Xiao Zheng; Fan Wang; Chi Yung Yam; Yan Mo; GuanHua Chen

2007-02-27T23:59:59.000Z

58

The benchmark of gutzwiller density functional theory in hydrogen systems  

SciTech Connect (OSTI)

We propose an approximate form of the exchange-correlation energy functional for the Gutzwiller density functional theory. It satisfies certain physical constraints in both weak and strong electron correlation limits. We benchmark the Gutzwiller density functional approximation in the hydrogen systems, where the static correlation error is shown to be negligible. The good transferability is demonstrated by applications to the hydrogen molecule and some crystal structures.

Yao, Y.; Wang, Cai-Zhuang; Ho, Kai-Ming

2012-02-23T23:59:59.000Z

59

Density functional theory for self-bound systems  

E-Print Network [OSTI]

The density functional theory is extended to account for self-bound systems. To this end the Hohenberg-Kohn theorem is formulated for the intrinsic density and a Kohn-Sham like procedure for an $N$--body system is derived using the adiabatic approximation to account for the center of mass motion.

Nir Barnea

2007-11-06T23:59:59.000Z

60

Classical density functional theory to tackle solvation in molecular liquids  

E-Print Network [OSTI]

We present a brief review of the classical density functional theory of atomic and molecular fluids. We focus on the application of the theory to the determination of the solvation properties of arbitrary molecular solutes in arbitrary molecular solvent. This includes the prediction of the solvation free energies, as well as the characterization of the microscopic, three-dimensional solvent structure.

Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Optimal-transport formulation of electronic density-functional theory  

E-Print Network [OSTI]

The most challenging scenario for Kohn-Sham density functional theory, that is when the electrons move relatively slowly trying to avoid each other as much as possible because of their repulsion (strong-interaction limit), is reformulated here as an optimal transport (or mass transportation theory) problem, a well established field of mathematics and economics. In practice, we show that solving the problem of finding the minimum possible internal repulsion energy for $N$ electrons in a given density $\\rho(\\rv)$ is equivalent to find the optimal way of transporting $N-1$ times the density $\\rho$ into itself, with cost function given by the Coulomb repulsion. We use this link to put the strong-interaction limit of density functional theory on firm grounds and to discuss the potential practical aspects of this reformulation.

Giuseppe Buttazzo; Luigi De Pascale; Paola Gori-Giorgi

2012-05-21T23:59:59.000Z

62

Subsystem functionals in density-functional theory: Investigating the exchange energy per particle R. Armiento*  

E-Print Network [OSTI]

Subsystem functionals in density-functional theory: Investigating the exchange energy per particle; published 31 October 2002 A viable way of extending the successful use of density-functional theory for slowly varying densities and discuss the implications of our findings on the future of functional

Armiento, Rickard

63

ORBITAL FUNCTIONALS IN STATIC AND TIME-DEPENDENT DENSITY FUNCTIONAL THEORY  

E-Print Network [OSTI]

ORBITAL FUNCTIONALS IN STATIC AND TIME-DEPENDENT DENSITY FUNCTIONAL THEORY E.K.U. Gross, T-97074 Wurzburg Germany INTRODUCTION Density functional theory (DFT) is among the most powerful quantum statements: 1 #12; 1. The ground-state density n uniquely determines the ground-state wave function [n

Gross, E.K.U.

64

Parameter-free calculation of response functions in time dependent density functional theory  

E-Print Network [OSTI]

Parameter-free calculation of response functions in time dependent density functional theory - Quasiparticle approach - Density functional approach Mapping theory to describe spectra of solids in TDDFT Towards an efficient (fast) theory Conclusions #12;Dielectric function of the material Vtot = -1 Vext Non

Botti, Silvana

65

Correlation Testing in Nuclear Density Functional Theory  

E-Print Network [OSTI]

Correlation testing provides a quick method of discriminating amongst potential terms to include in a nuclear mass formula or functional and is a necessary tool for further nuclear mass models; however a firm mathematical foundation of the method has not been previously set forth. Here, the necessary justification for correlation testing is developed and more detail of the motivation behind its use is give. Examples are provided to clarify the method analytically and for computational benchmarking. We provide a quantitative demonstration of the method's performance and short-comings, highlighting also potential issues a user may encounter. In concluding we suggest some possible future developments to improve the limitations of the method.

M. G. Bertolli

2012-08-07T23:59:59.000Z

66

Density functional theory and optimal transportation with Coulomb cost  

E-Print Network [OSTI]

We present here novel insight into exchange-correlation functionals in density functional theory, based on the viewpoint of optimal transport. We show that in the case of two electrons and in the semiclassical limit, the exact exchange-correlation functional reduces to a very interesting functional of novel form, which depends on an optimal transport map $T$ associated with a given density $\\rho$. Since the above limit is strongly correlated, the limit functional yields insight into electron correlations. We prove the existence and uniqueness of such an optimal map for any number of electrons and each $\\rho$, and determine the map explicitly in the case when $\\rho$ is radially symmetric.

Codina Cotar; Gero Friesecke; Claudia Klppelberg

2011-04-04T23:59:59.000Z

67

Particle vibrational coupling in covariant density functional theory  

E-Print Network [OSTI]

A consistent combination of covariant density functional theory (CDFT) and Landau-Migdal Theory of Finite Fermi Systems (TFFS) is presented. Both methods are in principle exact, but Landau-Migdal theory cannot describe ground state properties and density functional theory does not take into account the energy dependence of the self-energy and therefore fails to yield proper single-% particle spectra as well as the coupling to complex configurations in the width of giant resonances. Starting from an energy functional, phonons and their vertices are calculated without any further parameters. They form the basis of particle-vibrational coupling leading to an energy dependence of the self-energy and an induced energy-dependent interaction in the response equation. A subtraction procedure avoids double counting. Applications in doubly magic nuclei and in a chain of superfluid nuclei show excellent agreement with experimental data.

P. Ring; E. Litvinova

2010-06-21T23:59:59.000Z

68

A Classical Density-Functional Theory for Describing Water Interfaces  

E-Print Network [OSTI]

We develop a classical density functional for water which combines the White Bear fundamental-measure theory (FMT) functional for the hard sphere fluid with attractive interactions based on the Statistical Associating Fluid Theory (SAFT-VR). This functional reproduces the properties of water at both long and short length scales over a wide range of temperatures, and is computationally efficient, comparable to the cost of FMT itself. We demonstrate our functional by applying it to systems composed of two hard rods, four hard rods arranged in a square and hard spheres in water.

Jessica Hughes; Eric Krebs; David Roundy

2012-08-31T23:59:59.000Z

69

Introduction to Density Functional Theory and Exchange-Correlation Energy Functionals  

E-Print Network [OSTI]

Introduction to Density Functional Theory and Exchange-Correlation Energy Functionals R. O. Jones.jones@fz-juelich.de Density functional calculations of cohesive and structural properties of molecules and solids can the theory and discuss the local density approximations basic to most applications, and we discuss ways

70

Improved association in a classical density functional theory for water  

SciTech Connect (OSTI)

We present a modification to our recently published statistical associating fluid theory-based classical density functional theory for water. We have recently developed and tested a functional for the averaged radial distribution function at contact of the hard-sphere fluid that is dramatically more accurate at interfaces than earlier approximations. We now incorporate this improved functional into the association term of our free energy functional for water, improving its description of hydrogen bonding. We examine the effect of this improvement by studying two hard solutes (a hard hydrophobic rod and a hard sphere) and a Lennard-Jones approximation of a krypton atom solute. The improved functional leads to a moderate change in the density profile and a large decrease in the number of hydrogen bonds broken in the vicinity of the hard solutes. We find an improvement of the partial radial distribution for a krypton atom in water when compared with experiment.

Krebs, Eric J.; Schulte, Jeff B.; Roundy, David [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States)] [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States)

2014-03-28T23:59:59.000Z

71

Addressing spectroscopic quality of covariant density functional theory  

E-Print Network [OSTI]

The spectroscopic quality of covariant density functional theory has been accessed by analyzing the accuracy and theoretical uncertainties in the description of spectroscopic observables. Such analysis is first presented for the energies of the single-particle states in spherical and deformed nuclei. It is also shown that the inclusion of particle-vibration coupling improves the description of the energies of predominantly single-particle states in medium and heavy-mass spherical nuclei. However, the remaining differences between theory and experiment clearly indicate missing physics and missing terms in covariant energy density functionals. The uncertainties in the predictions of the position of two-neutron drip line sensitively depend on the uncertainties in the prediction of the energies of the single-particle states. On the other hand, many spectroscopic observables in well deformed nuclei at ground state and finite spin only weakly depend on the choice of covariant energy density functional.

A. V. Afanasjev

2014-09-17T23:59:59.000Z

72

Effective Maxwell equations from time-dependent density functional theory  

E-Print Network [OSTI]

The behavior of interacting electrons in a perfect crystal under macroscopic external electric and magnetic fields is studied. Effective Maxwell equations for the macroscopic electric and magnetic fields are derived starting from time-dependent density functional theory. Effective permittivity and permeability coefficients are obtained.

Weinan E; Jianfeng Lu; Xu Yang

2010-10-23T23:59:59.000Z

73

Density Functional Theory-Based Database Development and CALPHAD Automation  

E-Print Network [OSTI]

Density Functional Theory-Based Database Development and CALPHAD Automation YI WANG,1,2 SHUNLI, the integration of first-principles calculations, CALPHAD modeling, and the automation of phase diagram, and the automated calculation of a phase diagram for the Al- Mg system. INTRODUCTION In thermodynamics, a phase

Chen, Long-Qing

74

Taming Density Functional Theory by Coarse-Graining  

E-Print Network [OSTI]

The standard (``fine-grained'') interpretation of quantum density functional theory, in which densities are specified with infinitely-fine spatial resolution, is mathematically unruly. Here, a coarse-grained version of DFT, featuring limited spatial resolution, and its relation to the fine-grained theory in the $L^1\\cap L^3$ formulation of Lieb, is studied, with the object of showing it to be not only mathematically well-behaved, but consonant with the spirit of DFT, practically (computationally) adequate and sufficiently close to the standard interpretation as to accurately reflect its non-pathological properties. The coarse-grained interpretation is shown to be a good model of formal DFT in the sense that: all densities are (ensemble)-V-representable; the intrinsic energy functional $F$ is a continuous function of the density and the representing external potential is the (directional) functional derivative of the intrinsic energy. Also, the representing potential $v[\\rho]$ is quasi-continuous, in that $v[\\rho]\\rho$ is continuous as a function of $\\rho$. The limit of coarse-graining scale going to zero is studied to see if convergence to the non-pathological aspects of the fine-grained theory is adequate to justify regarding coarse-graining as a good approximation. Suitable limiting behaviors or intrinsic energy, densities and representing potentials are found. Intrinsic energy converges monotonically, coarse-grained densities converge uniformly strongly to their low-intrinsic-energy fine-grainings, and $L^{3/2}+L^\\infty$ representability of a density is equivalent to the existence of a convergent sequence of coarse-grained potential/ground-state density pairs.

Paul E. Lammert

2010-08-10T23:59:59.000Z

75

Hybrid Dynamic Density Functional Theory for Polymer Melts and Blends  

E-Print Network [OSTI]

We propose a high-speed and accurate hybrid dynamic density functional theory for the computer simulations of the phase separation processes of polymer melts and blends. The proposed theory is a combination of the dynamic self-consistent field (SCF) theory and a time-dependent Ginzburg-Landau type theory with the random phase approximation (GRPA). The SCF theory is known to be accurate in evaluating the free energy of the polymer systems in both weak and strong segregation regions although it has a disadvantage of the requirement of a considerable amount of computational cost. On the other hand, the GRPA theory has an advantage of much smaller amount of required computational cost than the SCF theory while its applicability is limited to the weak segregation region. To make the accuracy of the SCF theory and the high-performance of the GRPA theory compatible, we adjust the chemical potential of the GRPA theory by using the SCF theory every constant time steps in the dynamic simulations. The performance of the GRPA and the hybrid theories is tested by using several systems composed of an A/B homopolymer, an AB diblock copolymer, or an ABC triblock copolymer. Using the hybrid theory, we succeeded in reproducing the metastable complex phase-separated domain structures of an ABC triblock copolymer observed by experiments.

Takashi Honda; Toshihiro Kawakatsu

2006-09-05T23:59:59.000Z

76

Ions in solution: Density corrected density functional theory (DC-DFT)  

SciTech Connect (OSTI)

Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HOCl{sup ?} and HOH{sub 2}O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent.

Kim, Min-Cheol; Sim, Eunji, E-mail: esim@yonsei.ac.kr [Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 (Korea, Republic of)] [Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Burke, Kieron [Department of Chemistry, University of California, Irvine, California 92697 (United States)] [Department of Chemistry, University of California, Irvine, California 92697 (United States)

2014-05-14T23:59:59.000Z

77

Nuclear Density Functional Theory and the Equation of State  

E-Print Network [OSTI]

A nuclear density functional can be used to find the binding energy and shell structure of nuclei and the energy gap in superconducting nuclear matter. In this paper, we study the possible application of a nuclear density functional theory to nuclear astrophysics. From energy density functional theory, we can deduce the interaction between nucleons to find a rough estimate of the charge radius of the specific nuclei. Compared to the Finite-Range Thomas Fermi model, we include three-body forces, which might be important at densities several times that of nuclear matter density. We also add the momentum dependent interaction to take into account the effective mass of the nucleons. We study matter in the neutron star crust using the Wigner-Seitz cell method. By constructing the mass-radius relation of neutron stars and investigating lepton-rich nuclear matter in proto-neutron stars, we find that the density functional can be used to construct an equation of state of hot dense matter.

Yeunhwan Lim

2011-04-06T23:59:59.000Z

78

Model hamiltonians in density functional theory Paola Gori-Giorgi, Julien Toulouse, and Andreas Savin  

E-Print Network [OSTI]

Model hamiltonians in density functional theory Paola Gori-Giorgi, Julien Toulouse, and Andreas, density functional theory. 1 hal-00981803,version1-22Apr2014 Author manuscript, published in "High (density functional theory [3], and density matrix functional theory [4], that is somehow in between

Paris-Sud XI, Université de

79

Relativistic density functional theory for finite nuclei and neutron stars  

E-Print Network [OSTI]

The main goal of the present contribution is a pedagogical introduction to the fascinating world of neutron stars by relying on relativistic density functional theory. Density functional theory provides a powerful--and perhaps unique--framework for the calculation of both the properties of finite nuclei and neutron stars. Given the enormous densities that may be reached in the core of neutron stars, it is essential that such theoretical framework incorporates from the outset the basic principles of Lorentz covariance and special relativity. After a brief historical perspective, we present the necessary details required to compute the equation of state of dense, neutron-rich matter. As the equation of state is all that is needed to compute the structure of neutron stars, we discuss how nuclear physics--particularly certain kind of laboratory experiments--can provide significant constrains on the behavior of neutron-rich matter.

Piekarewicz, J

2015-01-01T23:59:59.000Z

80

Advances in Quantum Chemistry, 43, 95-117 (2003) Differentiability in density-functional theory  

E-Print Network [OSTI]

Advances in Quantum Chemistry, 43, 95-117 (2003) Differentiability in density-functional theory in density-functional theory (DFT) is investigated, and it is shown that the so-called Levy- Lieb functional The differentiability of density functionals is of fundamental importance in Density-Functional Theory (DFT) and forms

Lindgren, Ingvar

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Dynamics of localized particles from density functional theory  

E-Print Network [OSTI]

A fundamental assumption of the dynamical density functional theory (DDFT) of colloidal systems is that a grand-canonical free energy functional may be employed to generate the thermodynamic driving forces. Using one-dimensional hard-rods as a model system we analyze the validity of this key assumption and show that unphysical self-interactions of the tagged particle density fields, arising from coupling to a particle reservoir, are responsible for the excessively fast relaxation predicted by the theory. Moreover, our findings suggest that even employing a canonical functional would not lead to an improvement for many-particle systems, if only the total density is considered. We present several possible schemes to suppress these effects by incorporating tagged densities. When applied to confined systems we demonstrate, using a simple example, that DDFT neccessarily leads to delocalized tagged particle density distributions, which do not respect the fundamental geometrical contraints apparent in Brownian dynamics simulation data. The implication of these results for possible applications of DDFT to treat the glass transition are discussed.

Johannes Reinhardt; Joseph Michael Brader

2011-11-23T23:59:59.000Z

82

Differentiable but exact formulation of density-functional theory  

SciTech Connect (OSTI)

The universal density functional F of density-functional theory is a complicated and ill-behaved function of the densityin particular, F is not differentiable, making many formal manipulations more complicated. While F has been well characterized in terms of convex analysis as forming a conjugate pair (E, F) with the ground-state energy E via the HohenbergKohn and Lieb variation principles, F is nondifferentiable and subdifferentiable only on a small (but dense) subset of its domain. In this article, we apply a tool from convex analysis, MoreauYosida regularization, to construct, for any ? > 0, pairs of conjugate functionals ({sup ?}E, {sup ?}F) that converge to (E, F) pointwise everywhere as ? ? 0{sup +}, and such that {sup ?}F is (Frchet) differentiable. For technical reasons, we limit our attention to molecular electronic systems in a finite but large box. It is noteworthy that no information is lost in the MoreauYosida regularization: the physical ground-state energy E(v) is exactly recoverable from the regularized ground-state energy {sup ?}E(v) in a simple way. All concepts and results pertaining to the original (E, F) pair have direct counterparts in results for ({sup ?}E, {sup ?}F). The MoreauYosida regularization therefore allows for an exact, differentiable formulation of density-functional theory. In particular, taking advantage of the differentiability of {sup ?}F, a rigorous formulation of KohnSham theory is presented that does not suffer from the noninteracting representability problem in standard KohnSham theory.

Kvaal, Simen, E-mail: simen.kvaal@kjemi.uio.no; Ekstrm, Ulf; Helgaker, Trygve [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway)] [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); Teale, Andrew M. [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway) [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

2014-05-14T23:59:59.000Z

83

Symmetry Projected Density Functional Theory and Neutron Halos  

E-Print Network [OSTI]

The appearance of halo phenomena near the drip line nuclei has challenged our traditional understanding of the nuclei as an incompressible charged liquid drop and extended nuclear physics to low density and inhomogeneous system, where the coupling to the continuum has to be treated in a consistent way. Recently Relativistic Hartree Bogoliubov (RHB) theory in the continuum has been applied successfully to the description of halo phenomena in light and medium heavy nuclei [1, 2, 3]. This theory provides a self-consistent treatment of pairing correlation in the presence of the continuum and allows a microscopic description of halo phenomena in the framework of density functional theory. Essential conditions for the formation of a neutron halo have been found: (a) the Fermi surface of the neutrons has to

unknown authors

84

Phase-space explorations in time-dependent density functional theory A.K. Rajam a  

E-Print Network [OSTI]

Phase-space explorations in time-dependent density functional theory A.K. Rajam a , Paul Hessler b online xxxx Keywords: Time-dependent density functional theory Phase-space Momentum-distributions Density to phase-space densities, discuss some formal aspects of such a ``phase-space density functional theory

85

Curvature and Frontier Orbital Energies in Density Functional Theory  

SciTech Connect (OSTI)

Perdew et al. [Phys. Rev. Lett 49, 1691 (1982)] discovered and proved two different properties that exact Kohn-Sham density functional theory (DFT) must obey: (i) The exact total energy versus particle number must be a series of linear segments between integer electron points; (ii) Across an integer number of electrons, the exchange-correlation potential may ``jump by a constant, known as the derivative discontinuity (DD). Here, we show analytically that in both the original and the generalized Kohn-Sham formulation of DFT, the two are in fact two sides of the same coin. Absence of a derivative discontinuity necessitates deviation from piecewise linearity, and the latter can be used to correct for the former, thereby restoring the physical meaning of the orbital energies. Using selected small molecules, we show that this results in a simple correction scheme for any underlying functional, including semi-local and hybrid functionals as well as Hartree-Fock theory, suggesting a practical correction for the infamous gap problem of density functional theory. Moreover, we show that optimally-tuned range-separated hybrid functionals can inherently minimize both DD and curvature, thus requiring no correction, and show that this can be used as a sound theoretical basis for novel tuning strategies.

Stein, Tamar; Autschbach, Jochen; Govind, Niranjan; Kronik, Leeor; Baer, Roi

2012-12-20T23:59:59.000Z

86

Density functional theory for Baxter's sticky hard spheres in confinement  

E-Print Network [OSTI]

It has recently been shown that a free energy for Baxter's sticky hard sphere fluid is uniquely defined within the framework of fundamental measure theory (FMT) for the inhomogeneous hard sphere fluid, provided that it obeys scaled-particle theory and the Percus-Yevick (PY) result for the direct correlation function [Hansen-Goos and Wettlaufer, J. Chem. Phys. {\\bf 134}, 014506 (2011)]. Here, combining weighted densities from common versions of FMT with a new vectorial weighted density, we derive a regularization of the divergences of the associated strongly confined limit. Moreover, the simple free energy that emerges is exact in the zero-dimensional limit, leaves the underlying equation of state unaffected, and yields a direct correlation function distinct from the PY expression. Comparison with simulation data for both the bulk pair correlation function and the density profiles in confinement shows that the new theory is significantly more accurate than the PY-based results. Finally, the resulting free energy is applicable to a glass of adhesive hard spheres.

Hendrik Hansen-Goos; Mark A. Miller; J. S. Wettlaufer

2011-12-15T23:59:59.000Z

87

Deformed one-quasiparticle states in covariant density functional theory  

E-Print Network [OSTI]

Systematic investigation of the accuracy of the description of the energies of deformed one-quasiparticle states has been performed in covariant density functional theory in actinide and rare-earth mass regions. The sources of the discrepancies between theory and experiment are analyzed. Although some improvements in the description of ground state configurations and one-quasiparticle spectra can be achieved by better parametrization of the relativistic mean field Lagrangian, the analysis suggests that spectroscopic quality of their description can be achieved only in theoretical framework which takes into account particle-vibration coupling.

A. V. Afanasjev; S. Shawaqfeh

2012-05-10T23:59:59.000Z

88

Atomistic force field for alumina fit to density functional theory  

SciTech Connect (OSTI)

We present a force field for bulk alumina (Al{sub 2}O{sub 3}), which has been parametrized by fitting the energies, forces, and stresses of a large database of reference configurations to those calculated with density functional theory (DFT). We use a functional form that is simpler and computationally more efficient than some existing models of alumina parametrized by a similar technique. Nevertheless, we demonstrate an accuracy of our potential that is comparable to those existing models and to DFT. We present calculations of crystal structures and energies, elastic constants, phonon spectra, thermal expansion, and point defect formation energies.

Sarsam, Joanne [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom) [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Thomas Young Centre, Imperial College London, London SW7 2AZ (United Kingdom); Finnis, Michael W.; Tangney, Paul, E-mail: p.tangney@imperial.ac.uk [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom) [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Thomas Young Centre, Imperial College London, London SW7 2AZ (United Kingdom); Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom)

2013-11-28T23:59:59.000Z

89

Subsystem real-time Time Dependent Density Functional Theory  

E-Print Network [OSTI]

We present the extension of Frozen Density Embedding (FDE) theory to real-time Time Dependent Density Functional Theory (rt-TDDFT). FDE a is DFT-in-DFT embedding method that allows to partition a larger Kohn-Sham system into a set of smaller, coupled Kohn-Sham systems. Additional to the computational advantage, FDE provides physical insight into the properties of embedded systems and the coupling interactions between them. The extension to rt-TDDFT is done straightforwardly by evolving the Kohn-Sham subsystems in time simultaneously, while updating the embedding potential between the systems at every time step. Two main applications are presented: the explicit excitation energy transfer in real time between subsystems is demonstrated for the case of the Na$_4$ cluster and the effect of the embedding on optical spectra of coupled chromophores. In particular, the importance of including the full dynamic response in the embedding potential is demonstrated.

Krishtal, Alisa; Pavanello, Michele

2015-01-01T23:59:59.000Z

90

A Wigner Monte Carlo approach to density functional theory  

SciTech Connect (OSTI)

In order to simulate quantum N-body systems, stationary and time-dependent density functional theories rely on the capacity of calculating the single-electron wave-functions of a system from which one obtains the total electron density (KohnSham systems). In this paper, we introduce the use of the Wigner Monte Carlo method in ab-initio calculations. This approach allows time-dependent simulations of chemical systems in the presence of reflective and absorbing boundary conditions. It also enables an intuitive comprehension of chemical systems in terms of the Wigner formalism based on the concept of phase-space. Finally, being based on a Monte Carlo method, it scales very well on parallel machines paving the way towards the time-dependent simulation of very complex molecules. A validation is performed by studying the electron distribution of three different systems, a Lithium atom, a Boron atom and a hydrogenic molecule. For the sake of simplicity, we start from initial conditions not too far from equilibrium and show that the systems reach a stationary regime, as expected (despite no restriction is imposed in the choice of the initial conditions). We also show a good agreement with the standard density functional theory for the hydrogenic molecule. These results demonstrate that the combination of the Wigner Monte Carlo method and KohnSham systems provides a reliable computational tool which could, eventually, be applied to more sophisticated problems.

Sellier, J.M., E-mail: jeanmichel.sellier@gmail.com; Dimov, I.

2014-08-01T23:59:59.000Z

91

Time-dependent Density Functional Theory Miguel A. L. Marques and E. K. U. Gross  

E-Print Network [OSTI]

Time-dependent Density Functional Theory Miguel A. L. Marques and E. K. U. Gross 1 Introduction Time-dependent density-functional theory (TDDFT) extends the basic ideas of ground-state density-functional is the one-body electron density, n(r, t). The advantages are clear: The many-body wave-function, a function

Wu, Zhigang

92

Time-dependent current density functional theory on a lattice  

E-Print Network [OSTI]

A rigorous formulation of time-dependent current density functional theory (TDCDFT) on a lattice is presented. The density-to-potential mapping and the ${\\cal V}$-representability problems are reduced to a solution of a certain nonlinear lattice Schr\\"odinger equation, to which the standard existence and uniqueness results for nonliner differential equations are applicable. For two versions of the lattice TDCDFT we prove that any continuous in time current density is locally ${\\cal V}$-representable (both interacting and noninteracting), provided in the initial state the local kinetic energy is nonzero everywhere. In most cases of physical interest the ${\\cal V}$-representability should also hold globally in time. These results put the application of TDCDFT to any lattice model on a firm ground, and open a way for studying exact properties of exchange correlation potentials.

I. V. Tokatly

2010-11-11T23:59:59.000Z

93

PHYSICAL REVIEW C 77, 064308 (2008) Effective shell model Hamiltonians from density functional theory: Quadrupolar and  

E-Print Network [OSTI]

for mapping a self-consistent mean-field theory (also known as density functional theory) onto a shell-state solution of this density functional theory at the Hartree-Fock plus BCS level, an effective shell-consistent mean-field (SCMF) approximation [1], also known as density functional theory (DFT

Bertsch George F.

94

On the Derivation of a Density Functional Theory for Microphase Separation of Diblock Copolymers  

E-Print Network [OSTI]

On the Derivation of a Density Functional Theory for Microphase Separation of Diblock Copolymers in copolymer melts. The Ohta-Kawasaki density functional theory gives rise to a nonlocal Cahn copolymers, mean field theory, density functional theory. 1 Introduction A diblock copolymer is a linear

Ren, Xiaofeng

95

Excitations and benchmark ensemble density functional theory for two electrons  

SciTech Connect (OSTI)

A new method for extracting ensemble Kohn-Sham potentials from accurate excited state densities is applied to a variety of two-electron systems, exploring the behavior of exact ensemble density functional theory. The issue of separating the Hartree energy and the choice of degenerate eigenstates is explored. A new approximation, spin eigenstate Hartree-exchange, is derived. Exact conditions that are proven include the signs of the correlation energy components and the asymptotic behavior of the potential for small weights of the excited states. Many energy components are given as a function of the weights for two electrons in a one-dimensional flat box, in a box with a large barrier to create charge transfer excitations, in a three-dimensional harmonic well (Hooke's atom), and for the He atom singlet-triplet ensemble, singlet-triplet-singlet ensemble, and triplet bi-ensemble.

Pribram-Jones, Aurora; Burke, Kieron [Department of Chemistry, University of California-Irvine, Irvine, California 92697 (United States)] [Department of Chemistry, University of California-Irvine, Irvine, California 92697 (United States); Yang, Zeng-hui; Ullrich, Carsten A. [Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States)] [Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States); Trail, John R.; Needs, Richard J. [Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)] [Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)

2014-05-14T23:59:59.000Z

96

Uncertainty Quantification and Propagation in Nuclear Density Functional Theory  

E-Print Network [OSTI]

Nuclear density functional theory (DFT) is one of the main theoretical tools used to study the properties of heavy and superheavy elements, or to describe the structure of nuclei far from stability. While on-going efforts seek to better root nuclear DFT in the theory of nuclear forces [see Duguet et al., this issue], energy functionals remain semi-phenomenological constructions that depend on a set of parameters adjusted to experimental data in finite nuclei. In this paper, we review recent efforts to quantify the related uncertainties, and propagate them to model predictions. In particular, we cover the topics of parameter estimation for inverse problems, statistical analysis of model uncertainties and Bayesian inference methods. Illustrative examples are taken from the literature.

N. Schunck; J. D. McDonnell; D. Higdon; J. Sarich; S. M. Wild

2015-03-19T23:59:59.000Z

97

Quantification of Uncertainties in Nuclear Density Functional theory  

E-Print Network [OSTI]

Reliable predictions of nuclear properties are needed as much to answer fundamental science questions as in applications such as reactor physics or data evaluation. Nuclear density functional theory is currently the only microscopic, global approach to nuclear structure that is applicable throughout the nuclear chart. In the past few years, a lot of effort has been devoted to setting up a general methodology to assess theoretical uncertainties in nuclear DFT calculations. In this paper, we summarize some of the recent progress in this direction. Most of the new material discussed here will be be published in separate articles.

N. Schunck; J. D. McDonnell; D. Higdon; J. Sarich; S. Wild

2014-09-17T23:59:59.000Z

98

Augmented Lagrangian Method for Constrained Nuclear Density Functional Theory  

E-Print Network [OSTI]

The augmented Lagrangiam method (ALM), widely used in quantum chemistry constrained optimization problems, is applied in the context of the nuclear Density Functional Theory (DFT) in the self-consistent constrained Skyrme Hartree-Fock-Bogoliubov (CHFB) variant. The ALM allows precise calculations of multidimensional energy surfaces in the space of collective coordinates that are needed to, e.g., determine fission pathways and saddle points; it improves accuracy of computed derivatives with respect to collective variables that are used to determine collective inertia; and is well adapted to supercomputer applications.

A. Staszczak; M. Stoitsov; A. Baran; W. Nazarewicz

2010-07-21T23:59:59.000Z

99

Descriptions of carbon isotopes within the energy density functional theory  

SciTech Connect (OSTI)

Within the energy density functional (EDF) theory, the structure properties of Carbon isotopes are systematically studied. The shell model calculations are done for both even-A and odd-A nuclei, to study the structure of rich-neutron Carbon isotopes. The EDF theory indicates the single-neutron halo structures in {sup 15}C, {sup 17}C and {sup 19}C, and the two-neutron halo structures in {sup 16}C and {sup 22}C nuclei. It is also found that close to the neutron drip-line, there exist amazing increase in the neutron radii and decrease on the binding energies BE, which are tightly related with the blocking effect and correspondingly the blocking effect plays a significant role in the shell model configurations.

Ismail, Atef [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia and Department of Physics, Al-Azhar University, 71524 Assiut (Egypt); Cheong, Lee Yen; Yahya, Noorhana [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Tammam, M. [Department of Physics, Al-Azhar University, 71524 Assiut (Egypt)

2014-10-24T23:59:59.000Z

100

Recent progress in the study of fission barriers in covariant density functional theory  

E-Print Network [OSTI]

Recent progress in the study of fission barriers of actinides and superheavy nuclei within covariant density functional theory is overviewed.

A. V. Afanasjev; H. Abusara; P. Ring

2012-05-10T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Multicomponent density-functional theory for electrons and nuclei Thomas Kreibich  

E-Print Network [OSTI]

Multicomponent density-functional theory for electrons and nuclei Thomas Kreibich Institut für a general multicomponent density-functional theory in which electrons and nuclei are treated completely , 71.10. w I. INTRODUCTION Density-functional theory DFT is among the most suc- cessful approaches

Gross, E.K.U.

102

Intermolecular forces and nonbonded interactions: Superoperator nonlinear time-dependent density-functional-theory response approach  

E-Print Network [OSTI]

Intermolecular forces and nonbonded interactions: Superoperator nonlinear time-dependent density-functional-theory oscillator (CEO) eigenmodes of linearized time-dependent density-functional theory. Closed expressions response [35­38] with time- dependent density-functional theory (TDDFT) [21,39­43] to develop a systematic

Mukamel, Shaul

103

On the Floquet formulation of time-dependent density functional theory  

E-Print Network [OSTI]

On the Floquet formulation of time-dependent density functional theory Neepa T. Maitra *, Kieron by Elsevier Science B.V. Ground-state density functional theory (DFT) [1] has been tremendously successful generalized ground-state density functional theory to time-dependent problems (TDDFT) [4]. TDDFT has become

104

Electronic Structure: Density Functional Theory S. Kurth, M. A. L. Marques, and E. K. U. Gross  

E-Print Network [OSTI]

Electronic Structure: Density Functional Theory S. Kurth, M. A. L. Marques, and E. K. U. Gross: July 5, 2003) PACS numbers: 71.15.Mb, 31.15.Ew 1 #12;I. INTRODUCTION Density functional theory (DFT systems becomes prohibitive. A different approach is taken in density functional theory where, instead

Gross, E.K.U.

105

Spin-Multiplet Energies from Time-Dependent Density-Functional Theory  

E-Print Network [OSTI]

Spin-Multiplet Energies from Time-Dependent Density-Functional Theory M. Petersilka and E, density-functional theory (DFT) [1, 2, 3, 4, 5] has enjoyed increas- ing popularity in the #12;eld energies which is based on time-dependent density- functional theory (TDDFT) [26]. In the linear response

Gross, E.K.U.

106

Current density functional theory of spontaneously magnetised solids H. Ebert and Marco Battocletti  

E-Print Network [OSTI]

Current density functional theory of spontaneously magnetised solids H. Ebert and Marco Battocletti, 1997) The first application of current density functional theory (CDFT) to spontaneously magnetised to a plain calculation done within spin density functional theory (SDFT). Ms number LB6710. PACS numbers: 71

Gross, E.K.U.

107

Supplementary material to "Curvature and frontier orbital energies in density functional theory", by Stein et al.  

E-Print Network [OSTI]

Supplementary material to "Curvature and frontier orbital energies in density functional theory and frontier orbital energies in density functional theory", by Stein et al. 2. Calculation of curvature from: [{ }] [{ }] #12;Supplementary material to "Curvature and frontier orbital energies in density functional theory

Baer, Roi

108

Non-periodic finite-element formulation of KohnSham density functional theory  

E-Print Network [OSTI]

Non-periodic finite-element formulation of Kohn­Sham density functional theory Phanish-element formulation for Kohn­Sham density functional theory (KS-DFT). We transform the original variational problem, dislocations and crack tips using density functional theory (DFT) at reasonable computational cost by retaining

Ortiz, Michael

109

Weighted density functional theory of the solvophobic effect Sean X. Sun  

E-Print Network [OSTI]

Weighted density functional theory of the solvophobic effect Sean X. Sun Department of Chemistry be obtained from experimental data. Using these elements, we construct a spatial density functional theory naturally be cast in a simple picture based on the density functional theory DFT description of liquids

Sun, Sean

110

Efficient computation of the coupling matrix in Time-Dependent Density Functional Theory  

E-Print Network [OSTI]

Efficient computation of the coupling matrix in Time-Dependent Density Functional Theory Emmanuel arising in time-dependent density functional theory. The two important aspects involved, solution- dopotentials within density functional theory (DFT) [1]. This approach has been used to predict mechanical

Lorin, Emmanuel

111

Range-separated density-functional theory with random phase approximation: Detailed formalism and illustrative applications  

E-Print Network [OSTI]

Range-separated density-functional theory with random phase approximation: Detailed formalism-body theory, we present the details of a formally exact adiabatic-connection fluctuation-dissipation density-functional´an, Phys. Rev. Lett. 102, 096404 (2009). Range-separated density-functional theory approaches combining

Boyer, Edmond

112

Band structures Optical absorption Summary Key concepts in Density Functional Theory (II)  

E-Print Network [OSTI]

Band structures Optical absorption Summary Key concepts in Density Functional Theory (II) Kohn, Belfast Key concepts in Density Functional Theory (II) Silvana Botti #12;Band structures Optical in Density Functional Theory (II) Silvana Botti #12;Band structures Optical absorption Summary Outline 1 From

Botti, Silvana

113

6 Multicomponent Density-Functional Theory R. van Leeuwen and E.K.U. Gross  

E-Print Network [OSTI]

6 Multicomponent Density-Functional Theory R. van Leeuwen and E.K.U. Gross 6.1 Introduction fields. Our goal is to set up a time-dependent multicomponent density-functional theory (TDMCDFT.K.U. Gross: Multicomponent Density-Functional Theory, Lect. Notes Phys. 706, 93­106 (2006) DOI 10

Gross, E.K.U.

114

A mesh-free convex approximation scheme for KohnSham density functional theory  

E-Print Network [OSTI]

A mesh-free convex approximation scheme for Kohn­Sham density functional theory Phanish: Convex approximation scheme Mesh-free methods Kohn­Sham Density functional theory Maximum-entropy a b s t r a c t Density functional theory developed by Hohenberg, Kohn and Sham is a widely accepted

Ortiz, Michael

115

Double-hybrid density-functional theory with meta-generalized-gradient approximations  

E-Print Network [OSTI]

Double-hybrid density-functional theory with meta-generalized-gradient approximations Sidi Ould-parameter double-hybrid density-functional theory [K. Sharkas, J. Toulouse, and A. Savin, J. Chem. Phys. 134 of the most accurate approximations for electronic-structure calculations within density- functional theory

Paris-Sud XI, Université de

116

A mathematical perspective on density functional perturbation theory  

E-Print Network [OSTI]

In this article, we provide a mathematical analysis of the perturbation method for extended Kohn-Sham models, in which fractional occupation numbers are allowed. All our results are established in the framework of the reduced Hartree-Fock (rHF) model, but our approach can be used to study other kinds of extended Kohn-Sham models, under some assumptions on the mathematical structure of the exchange-correlation functional. The classical results of Density Functional Perturbation Theory in the non-degenerate case (that is when the Fermi level is not a degenerate eigenvalue of the mean-field Hamiltonian) are formalized, and a proof of Wigner's (2n + 1) rule is provided. We then focus on the situation when the Fermi level is a degenerate eigenvalue of the rHF Hamiltonian, which had not been considered so far.

Eric Cancs; Nahia Mourad

2014-05-06T23:59:59.000Z

117

PHYSICAL REVIEW B 89, 155112 (2014) Angular momentum dependent orbital-free density functional theory  

E-Print Network [OSTI]

-free density functional theory (OFDFT) directly solves for the ground-state electron density. It scales of the Hohenberg- Kohn theorems [1], density functional theory (DFT) has gained vast popularity as an extremelyPHYSICAL REVIEW B 89, 155112 (2014) Angular momentum dependent orbital-free density functional

Florian, Libisch

118

Superfluid Local Density Approximation: A Density Functional Theory Approach to the Nuclear Pairing Problem  

E-Print Network [OSTI]

I describe the foundation of a Density Functional Theory approach to include pairing correlations, which was applied to a variety of systems ranging from dilute fermions, to neutron stars and finite nuclei. Ground state properties as well as properties of excited states and time-dependent phenomena can be achieved in this manner within a formalism based on microscopic input.

Aurel Bulgac

2012-04-10T23:59:59.000Z

119

Metallophilic interactions from dispersion-corrected density-functional theory  

SciTech Connect (OSTI)

In this article, we present the first comprehensive study of metallophilic (aurophilic) interactions using dispersion-corrected density-functional theory. Dispersion interactions (an essential component of metallophilicity) are treated using the exchange-hole dipole moment (XDM) model. By comparing against coupled-cluster benchmark calculations on simple dimers, we show that LC-?PBE-XDM is a viable functional to study interactions between closed-shell transition metals and that it performs uniformly better than second-order Mller-Plesset theory, the basic computational technique used in previous works. We apply LC-?PBE-XDM to address several open questions regarding metallophilicity, such as the interplay between dispersion and relativistic effects, the interaction strength along group 11, the additivity of homo- and hetero-metallophilic effects, the stability of [E(AuPH{sub 3}){sub 4}]{sup +} cations (E = N, P, As, Sb), and the role of metallophilic effects in crystal packing. We find that relativistic effects explain the prevalence of aurophilicity not by stabilizing metal-metal contacts, but by preventing gold from forming ionic structures involving bridge anions (which are otherwise common for Ag and Cu) as a result of the increased electron affinity of the metal. Dispersion effects are less important than previously assumed and their stabilization contribution is relatively independent of the metal.

Otero-de-la-Roza, Alberto, E-mail: aoterodelaroza@ucmerced.edu; Mallory, Joel D.; Johnson, Erin R., E-mail: ejohnson29@ucmerced.edu [Chemistry and Chemical Biology, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343 (United States)

2014-05-14T23:59:59.000Z

120

Daubechies wavelets for linear scaling density functional theory  

SciTech Connect (OSTI)

We demonstrate that Daubechies wavelets can be used to construct a minimal set of optimized localized adaptively contracted basis functions in which the Kohn-Sham orbitals can be represented with an arbitrarily high, controllable precision. Ground state energies and the forces acting on the ions can be calculated in this basis with the same accuracy as if they were calculated directly in a Daubechies wavelets basis, provided that the amplitude of these adaptively contracted basis functions is sufficiently small on the surface of the localization region, which is guaranteed by the optimization procedure described in this work. This approach reduces the computational costs of density functional theory calculations, and can be combined with sparse matrix algebra to obtain linear scaling with respect to the number of electrons in the system. Calculations on systems of 10?000 atoms or more thus become feasible in a systematic basis set with moderate computational resources. Further computational savings can be achieved by exploiting the similarity of the adaptively contracted basis functions for closely related environments, e.g., in geometry optimizations or combined calculations of neutral and charged systems.

Mohr, Stephan [Institut fr Physik, Universitt Basel, Klingelbergstr. 82, 4056 Basel (Switzerland); Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France); Ratcliff, Laura E.; Genovese, Luigi; Caliste, Damien; Deutsch, Thierry [Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France); Boulanger, Paul [Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France); Institut Nel, CNRS and Universit Joseph Fourier, B.P. 166, 38042 Grenoble Cedex 09 (France); Goedecker, Stefan [Institut fr Physik, Universitt Basel, Klingelbergstr. 82, 4056 Basel (Switzerland)

2014-05-28T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Fundamental measure density functional theory studies on the freezing of binary hard-sphere and Lennard-Jones mixtures  

E-Print Network [OSTI]

Fundamental measure density functional theory studies on the freezing of binary hard are calculated using the fundamental measure density functional theory. Using the thermodynamic perturbation. INTRODUCTION Density functional theory DFT became a practical the- oretical tool for the calculation

Song, Xueyu

122

Existence of A Rigorous Density-Functional Theory for Open Electronic Systems  

E-Print Network [OSTI]

We prove that the electron density function of a real physical system can be uniquely determined by its values on any finite subsystem. This establishes the existence of a rigorous density-functional theory for any open electronic system. By introducing a new density functional for dissipative interactions between the reduced system and its environment, we subsequently develop a time-dependent density-functional theory which depends in principle only on the electron density of the reduced system.

Xiao Zheng; Fan Wang; GuanHua Chen

2006-05-11T23:59:59.000Z

123

Generalized time-dependent density-functional-theory response functions for spontaneous density fluctuations and nonlinear response: Resolving the causality paradox in real time  

E-Print Network [OSTI]

Generalized time-dependent density-functional-theory response functions for spontaneous density shifted the focus of elec- tronic structure theory from the many-body wave function to the charge density response and spontaneous fluctuations of many-electron systems. The pth-order density response functions

Mukamel, Shaul

124

Progress at the interface of wave-function and density-functional theories  

SciTech Connect (OSTI)

The Kohn-Sham (KS) potential of density-functional theory (DFT) emerges as the minimizing effective potential in a variational scheme that does not involve fixing the unknown single-electron density. Using Rayleigh Schroedinger (RS) perturbation theory (PT), we construct ab initio approximations for the energy difference, the minimization of which determines the KS potential directly - thereby bypassing DFT's traditional algorithm to search for the density that minimizes the total energy. From second-order RS PT, we obtain variationally stable energy differences to be minimized, solving the severe problem of variational collapse of orbital-dependent exchange-correlation functionals based on second-order RS PT.

Gidopoulos, Nikitas I. [ISIS, Rutherford Appleton Laboratory, STFC, Didcot, OX11 0QX, Oxon (United Kingdom)

2011-04-15T23:59:59.000Z

125

Alternative separation of exchange and correlation in density-functional theory R. Armiento*  

E-Print Network [OSTI]

Alternative separation of exchange and correlation in density-functional theory R. Armiento.245120 PACS number s : 71.15.Mb, 31.15.Ew Kohn-Sham KS density-functional theory1 DFT is a successful scheme on this approach by creating and deploying a local-density-approximation-type XC functional. Hence, this work

Armiento, Rickard

126

Density-Functional Theory for Triplet Superconductors K. Capelle E.K.U. Gross  

E-Print Network [OSTI]

Density-Functional Theory for Triplet Superconductors K. Capelle E.K.U. Gross Institut f Introduction The purpose of this work is to generalize the density-functional theory (DFT) for superur Theoretische Physik Universitat Wurzburg Am Hubland D-97074 Wurzburg Germany Abstract The density-functional

Gross, E.K.U.

127

COMMUNICATIONS Some reasons not to use spin projected density functional theory  

E-Print Network [OSTI]

COMMUNICATIONS Some reasons not to use spin projected density functional theory Joanne M. Wittbrodt Received 28 May 1996; accepted 9 August 1996 Spin unrestricted calculations using density functional theory surfaces calculated by density functional methods, just as spin projection can yield poor results

Schlegel, H. Bernhard

128

Pore Size Analysis of Activated Carbons from Argon and Nitrogen Porosimetry Using Density Functional Theory  

E-Print Network [OSTI]

Form: December 28, 1999 We present isotherms calculated from density functional theory. A similar set of density functional theory isotherms, previously reported for nitrogen adsorption on carbon Functional Theory Robert J. Dombrowski, Daniel R. Hyduke, and Christian M. Lastoskie* Department of Chemical

Lastoskie, Christian M.

129

Accelerating the convergence of the total energy evaluation in density functional theory calculations  

E-Print Network [OSTI]

Accelerating the convergence of the total energy evaluation in density functional theory.1063/1.2821101 I. INTRODUCTION Density functional theory DFT ,1,2 one of the most widely used first functional theory OO-DFT B. Zhou and Y. A. Wang, J. Chem. Phys. 124, 081107 2006 is that the second

Wang, Yan Alexander

130

Self-interaction corrections in density functional theory  

SciTech Connect (OSTI)

Self-interaction corrections for Kohn-Sham density functional theory are reviewed for their physical meanings, formulations, and applications. The self-interaction corrections get rid of the self-interaction error, which is the sum of the Coulomb and exchange self-interactions that remains because of the use of an approximate exchange functional. The most frequently used self-interaction correction is the Perdew-Zunger correction. However, this correction leads to instabilities in the electronic state calculations of molecules. To avoid these instabilities, several self-interaction corrections have been developed on the basis of the characteristic behaviors of self-interacting electrons, which have no two-electron interactions. These include the von Weizscker kinetic energy and long-range (far-from-nucleus) asymptotic correction. Applications of self-interaction corrections have shown that the self-interaction error has a serious effect on the states of core electrons, but it has a smaller than expected effect on valence electrons. This finding is supported by the fact that the distribution of self-interacting electrons indicates that they are near atomic nuclei rather than in chemical bonds.

Tsuneda, Takao, E-mail: ttsuneda@yamanashi.ac.jp [Fuel Cell Nanomaterials Center, University of Yamanashi, Kofu 400-0021 (Japan)] [Fuel Cell Nanomaterials Center, University of Yamanashi, Kofu 400-0021 (Japan); Hirao, Kimihiko [Computational Chemistry Unit, RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047 (Japan)] [Computational Chemistry Unit, RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047 (Japan)

2014-05-14T23:59:59.000Z

131

A long-range-corrected density functional that performs well for both ground-state properties and time-dependent density functional theory  

E-Print Network [OSTI]

and time-dependent density functional theory excitation energies, including charge-transfer excited states energies within time-dependent density functional theory, is systematically evaluated, and optimal values. THEORETICAL BACKGROUND Generalized gradient approximations GGAs in density functional theory DFT are quite

Herbert, John

132

Relationship of Quantum Entanglement to Density Functional Theory  

E-Print Network [OSTI]

The maximum von Neumann entropy principle subject to given constraints of mean values of some physical observables determines the density matrix. Similarly the stationary action principle in the case of time-dependent (dissipative) situations under similar constraints yields the density matrix. The free energy and measures of entanglement are expressed in terms of such a density matrix and thus define respective functionals of the mean values. In the light of several model calculations, it is found that the density matrix contains information about both quantum entanglement and phase transitions even though there may not be any direct relationship implied by one on the other.

A. K. Rajagopal; R. W. Rendell

2005-12-13T23:59:59.000Z

133

A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder*  

E-Print Network [OSTI]

A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder initio molecular dynamics in the generalized gradient approximation to density functional theory to store hydrogen with sufficient gravimetric and volumetric densities to be economi- cally practical

Ceder, Gerbrand

134

Supplementary data for "Relativistic density functional theory modeling of plutonium and  

E-Print Network [OSTI]

Supplementary data for "Relativistic density functional theory modeling of plutonium and americium equilibrium geometries of plutonium and americium oxide molecules (standard .xyz files separated by empty

Titov, Anatoly

135

Understanding the NMR shifts in paramagnetic transition metal oxides using density functional theory calculations  

E-Print Network [OSTI]

obvious. In this paper, we show by means of density functional theory DFT calcula- tions that a rationalUnderstanding the NMR shifts in paramagnetic transition metal oxides using density functional functional theory DFT calculations in the generalized gradient approximation. For each compound, we calculate

Ceder, Gerbrand

136

Ensemble-Density Functional Theory for Excited States L. N. Oliveira  

E-Print Network [OSTI]

Ensemble-Density Functional Theory for Excited States L. N. Oliveira Instituto de F#19;#16;sica e aspects of the ensemble-density functional approach to the calculation of excited state energies Functional Theory to excited states [1]. That approach, proposed originally by Theophilou [2], is analogous

Gross, E.K.U.

137

Density Functional Theory for Baxter's Sticky Hard Spheres in Confinement Hendrik Hansen-Goos,1  

E-Print Network [OSTI]

Density Functional Theory for Baxter's Sticky Hard Spheres in Confinement Hendrik Hansen-Goos,1 that it obeys scaled-particle theory and the Percus-Yevick (PY) result for the direct correlation function [H with simulation data for both the bulk pair-correlation function and the density profiles in confinement shows

Wettlaufer, John S.

138

Time-dependent density functional theory with ultrasoft pseudopotentials: Real-time electron propagation across a molecular junction  

E-Print Network [OSTI]

Time-dependent density functional theory with ultrasoft pseudopotentials: Real-time electron 2006 A practical computational scheme based on time-dependent density functional theory TDDFT density functional theory22 TDDFT . Density functional theory DFT 23 with the Kohn-Sham reference kinetic

Lin, Xi

139

Density Functional Theory Calculations of Mass Transport in UO2  

SciTech Connect (OSTI)

In this talk we present results of density functional theory (DFT) calculations of U, O and fission gas diffusion in UO{sub 2}. These processes all impact nuclear fuel performance. For example, the formation and retention of fission gas bubbles induce fuel swelling, which leads to mechanical interaction with the clad thereby increasing the probability for clad breach. Alternatively, fission gas can be released from the fuel to the plenum, which increases the pressure on the clad walls and decreases the gap thermal conductivity. The evolution of fuel microstructure features is strongly coupled to diffusion of U vacancies. Since both U and fission gas transport rates vary strongly with the O stoichiometry, it is also important to understand O diffusion. In order to better understand bulk Xe behavior in UO{sub 2{+-}x} we first calculate the relevant activation energies using DFT techniques. By analyzing a combination of Xe solution thermodynamics, migration barriers and the interaction of dissolved Xe atoms with U, we demonstrate that Xe diffusion predominantly occurs via a vacancy-mediated mechanism. Since Xe transport is closely related to diffusion of U vacancies, we have also studied the activation energy for this process. In order to explain the low value of 2.4 eV found for U migration from independent damage experiments (not thermal equilibrium) the presence of vacancy clusters must be included in the analysis. Next we investigate species transport on the (111) UO{sub 2} surface, which is motivated by the formation of small voids partially filled with fission gas atoms (bubbles) in UO{sub 2} under irradiation. Surface diffusion could be the rate-limiting step for diffusion of such bubbles, which is an alternative mechanism for mass transport in these materials. As expected, the activation energy for surface diffusion is significantly lower than for bulk transport. These results are further discussed in terms of engineering-scale fission gas release models. Finally, oxidation of UO{sub 2} and the importance of cluster formation for understanding thermodynamic and kinetic properties of UO{sub 2+x} are investigated.

Andersson, Anders D. [Los Alamos National Laboratory; Dorado, Boris [CEA; Uberuaga, Blas P. [Los Alamos National Laboratory; Stanek, Christopher R. [Los Alamos National Laboratory

2012-06-26T23:59:59.000Z

140

Current density partitioning in time-dependent current density functional theory  

SciTech Connect (OSTI)

We adapt time-dependent current density functional theory to allow for a fragment-based solution of the many-electron problem of molecules in the presence of time-dependent electric and magnetic fields. Regarding a molecule as a set of non-interacting subsystems that individually evolve under the influence of an auxiliary external electromagnetic vector-scalar potential pair, the partition 4-potential, we show that there are one-to-one mappings between this auxiliary potential, a sharply-defined set of fragment current densities, and the total current density of the system. The partition electromagnetic (EM) 4-potential is expressed in terms of the real EM 4-potential of the system and a gluing EM 4-potential that accounts for exchange-correlation effects and mutual interaction forces between fragments that are required to yield the correct electron dynamics. We prove the zero-force theorem for the fragmented system, establish a variational formulation in terms of action functionals, and provide a simple illustration for a charged particle in a ring.

Mosquera, Martn A. [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States)] [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Wasserman, Adam, E-mail: awasser@purdue.edu [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States) [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-05-14T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Recent developments in classical density functional theory: Internal energy functional and diagrammatic structure of fundamental measure theory  

E-Print Network [OSTI]

An overview of several recent developments in density functional theory for classical inhomogeneous liquids is given. We show how Levy's constrained search method can be used to derive the variational principle that underlies density functional theory. An advantage of the method is that the Helmholtz free energy as a functional of a trial one-body density is given as an explicit expression, without reference to an external potential as is the case in the standard Mermin-Evans proof by reductio ad absurdum. We show how to generalize the approach in order to express the internal energy as a functional of the one-body density distribution and of the local entropy distribution. Here the local chemical potential and the bulk temperature play the role of Lagrange multipliers in the Euler-Lagrange equations for minimiziation of the functional. As an explicit approximation for the free-energy functional for hard sphere mixtures, the diagrammatic structure of Rosenfeld's fundamental measure density unctional is laid out. Recent extensions, based on the Kierlik-Rosinberg scalar weight functions, to binary and ternary non-additive hard sphere mixtures are described.

M. Schmidt; M. Burgis; W. S. B. Dwandaru; G. Leithall; P. Hopkins

2012-12-27T23:59:59.000Z

142

Joint density-functional theory for electronic structure of solvated systems  

E-Print Network [OSTI]

We introduce a new form of density functional theory for the {\\em ab initio} description of electronic systems in contact with a molecular liquid environment. This theory rigorously joins an electron density-functional for the electrons of a solute with a classical density-functional theory for the liquid into a single variational principle for the free energy of the combined system. A simple approximate functional predicts, without any fitting of parameters to solvation data, solvation energies as well as state-of-the-art quantum-chemical cavity approaches, which require such fitting.

Sahak Petrosyan; Jean-Francois Briere; David Roundy; T. A. Arias

2007-02-09T23:59:59.000Z

143

Fundamental-measure density functional theory study of the crystal-melt interface of the hard sphere system  

E-Print Network [OSTI]

Fundamental-measure density functional theory study of the crystal-melt interface of the hard density functional theory. The equilibrium interfacial density profiles and interfacial free energies were value is 0.6 5,10 . For the past two decades a number of density functional theories were developed

Song, Xueyu

144

short course on density-functional theory lectures given at the Fudan University, Shanghai, January 11-15, 2010  

E-Print Network [OSTI]

short course on density-functional theory lectures given at the Fudan University, Shanghai, January transforms Lecture 2: Density-functional theory · the electronic ground state as a functional of the external-order derivatives from (density-functional) perturbation theory · the 2n+1 theorem · lattice dynamics from DFPT

Gong, Xingao

145

Non-perturbative calculation of molecular magnetic properties within current-density functional theory  

SciTech Connect (OSTI)

We present a novel implementation of KohnSham density-functional theory utilizing London atomic orbitals as basis functions. External magnetic fields are treated non-perturbatively, which enable the study of both magnetic response properties and the effects of strong fields, using either standard density functionals or current-density functionalsthe implementation is the first fully self-consistent implementation of the latter for molecules. Pilot applications are presented for the finite-field calculation of molecular magnetizabilities, hypermagnetizabilities, and nuclear magnetic resonance shielding constants, focusing on the impact of current-density functionals on the accuracy of the results. Existing current-density functionals based on the gauge-invariant vorticity are tested and found to be sensitive to numerical details of their implementation. Furthermore, when appropriately regularized, the resulting magnetic properties show no improvement over standard density-functional results. An advantage of the present implementation is the ability to apply density-functional theory to molecules in very strong magnetic fields, where the perturbative approach breaks down. Comparison with high accuracy full-configuration-interaction results show that the inadequacies of current-density approximations are exacerbated with increasing magnetic field strength. Standard density-functionals remain well behaved but fail to deliver high accuracy. The need for improved current-dependent density-functionals, and how they may be tested using the presented implementation, is discussed in light of our findings.

Tellgren, E. I., E-mail: erik.tellgren@kjemi.uio.no; Lange, K. K.; Ekstrm, U.; Helgaker, T. [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway)] [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); Teale, A. M., E-mail: andrew.teale@nottingham.ac.uk [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Furness, J. W. [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)] [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

2014-01-21T23:59:59.000Z

146

Dynamical density functional theory with hydrodynamic interactions and colloids in unstable traps  

E-Print Network [OSTI]

A density functional theory for colloidal dynamics is presented which includes hydrodynamic interactions between the colloidal particles. The theory is applied to the dynamics of colloidal particles in an optical trap which switches periodically in time from a stable to unstable confining potential. In the absence of hydrodynamic interactions, the resulting density breathing mode, exhibits huge oscillations in the trap center which are almost completely damped by hydrodynamic interactions. The predicted dynamical density fields are in good agreement with Brownian dynamics computer simulations.

M. Rex; H. Loewen

2008-03-13T23:59:59.000Z

147

Screening for high-performance piezoelectrics using high-throughput density functional theory  

E-Print Network [OSTI]

We present a large-scale density functional theory (DFT) investigation of the ABO3 chemical space in the perovskite crystal structure, with the aim of identifying those that are relevant for forming piezoelectric materials. ...

Armiento, Rickard R.

148

The Materials genome : rapid materials screening for renewable energy using high-throughput density functional theory  

E-Print Network [OSTI]

This thesis relates to the emerging field of high-throughput density functional theory (DFT) computation for materials design and optimization. Although highthroughput DFT is a promising new method for materials discovery, ...

Jain, Anubhav, Ph.D. Massachusetts Institute of Technology

2011-01-01T23:59:59.000Z

149

Charge transport, configuration interaction and Rydberg states under density functional theory  

E-Print Network [OSTI]

Density functional theory (DFT) is a computationally efficient formalism for studying electronic structure and dynamics. In this work, we develop DFT-based excited-state methods to study electron transport, Rydberg excited ...

Cheng, Chiao-Lun

2008-01-01T23:59:59.000Z

150

Curvature and Frontier Orbital Energies in Density Functional Theory Tamar Stein,  

E-Print Network [OSTI]

Curvature and Frontier Orbital Energies in Density Functional Theory Tamar Stein, Jochen Autschbach the frontier, highest occupied (HOMO), and lowest unoccupied (LUMO) Kohn-Sham (KS) orbital energies (OEs

Baer, Roi

151

Brief review related to the foundations of time-dependent density functional theory  

E-Print Network [OSTI]

The electron density $n(\\rb,t)$, which is the central tool of time-dependent density functional theory, is presently considered to be derivable from a one-body time-dependent potential $V(\\rb,t)$, via one-electron wave functions satisfying a time- dependent Schr\\"{o}dinger equation. This is here related via a generalized equation of motion to a Dirac density matrix now involving $t$. Linear response theory is then surveyed, with a special emphasis on the question of causality with respect to the density dependence of the potential. Extraction of $V(\\rb,t)$ for solvable models is also proposed.

Thomas A. Niehaus; Norman H. March

2009-04-28T23:59:59.000Z

152

Complex structure of electron and density functional theory  

E-Print Network [OSTI]

Effective model for electron as two particle system is considered. The first particle in the system is chargeless mass of electron. The second one is massless charge of electron. Based on this model it is shown that density of energy for the particle is proportional to the probability density and the following formula stands $\\rho_E(x)=mc^2\\rho(x)$.

K. Koshelev

2013-01-08T23:59:59.000Z

153

Accurate Ground-State Energies of Solids and Molecules from Time-Dependent Density-Functional Theory  

E-Print Network [OSTI]

-dissipation theorem with time-dependent density- functional theory. The key ingredient is a renormalization scheme be obtained from time- dependent density-functional theory (TDDFT) through the Dyson equation ð? ¼ KS ð? þ KS density-functional theory (DFT), one needs a rather involved approximation for the xc energy in order

Thygesen, Kristian

154

PHYSICAL REVIEW A 85, 052510 (2012) Propagation of initially excited states in time-dependent density-functional theory  

E-Print Network [OSTI]

-dependent density-functional theory Peter Elliott and Neepa T. Maitra Department of Physics and Astronomy, Hunter March 2012; published 22 May 2012) Many recent applications of time-dependent density functional theory-dependent density functional theory (TDDFT) is an exact reformulation of the time-dependent quantum mechanics

155

The many-body problem A solution: DFT HK theorems KS scheme Summary Key concepts in Density Functional Theory (I)  

E-Print Network [OSTI]

's University, Belfast Key concepts in Density Functional Theory (I) Silvana Botti #12;The many-body problem concepts in Density Functional Theory (I) Silvana Botti #12;The many-body problem A solution: DFT HK theorems KS scheme Summary Outline 1 The many-body problem 2 A solution: Density Functional Theory 3

Botti, Silvana

156

PHYSICAL REVIEW B 84, 014103 (2011) Screening for high-performance piezoelectrics using high-throughput density functional theory  

E-Print Network [OSTI]

-throughput density functional theory Rickard Armiento,1 Boris Kozinsky,2 Marco Fornari,3 and Gerbrand Ceder1 1-scale density functional theory (DFT) investigation of the ABO3 chemical space in the perovskite crystal-throughput density functional theory19,20 calculations. The last decades have seen a rapid increase of computational

Ceder, Gerbrand

157

Density-functional theory of freezing of quantum liquids at zero temperature using exact liquid-state linear response  

E-Print Network [OSTI]

Density-functional theory of freezing of quantum liquids at zero temperature using exact liquid the shortcomings of the currently popular density-functional approximate theories to describe 3d freezing distances. S0163-1829 97 04310-5 I. INTRODUCTION The modern density-functional theory DFT , which

Likos, Christos N.

158

in: "Density Functional Theory", edited by R.F. Nalewajski, Topics in Current Chemistry, Vol. 181, p. 81  

E-Print Network [OSTI]

in: "Density Functional Theory", edited by R.F. Nalewajski, Topics in Current Chemistry, Vol. 181, p. 81 Springer­Verlag Berlin Heidelberg 1996 Density functional theory of time­dependent phenomena E of density functional theory (DFT) is to describe an interacting many­particle system exclusively

Gross, E.K.U.

159

Quasiparticle band structure and density-functional theory: Single-particle excitations and band gaps in lattice models  

E-Print Network [OSTI]

ARTICLES Quasiparticle band structure and density-functional theory: Single-particle excitations-particle eigenvalues. Without rigorous basis even for the exact density-functional theory , these are often taken, eigenvalues obtained from density-functional theory DFT , and those from a corresponding LDA. Notable among

Hess, Daryl W.

160

Density-functional theory with optimized effective potential and self-interaction correction for ground states and autoionizing resonances  

E-Print Network [OSTI]

Density-functional theory with optimized effective potential and self-interaction correction-interaction-free density-functional theory DFT for the treatment of both the static prop- erties of the ground states and Sham 2 , the density-functional theory DFT has undergone significant theoretical and computational ad

Chu, Shih-I

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

in: "Density Functional Theory", edited by R.F. Nalewajski, Topics in Current Chemistry, Vol. 181, p. 81  

E-Print Network [OSTI]

in: "Density Functional Theory", edited by R.F. Nalewajski, Topics in Current Chemistry, Vol. 181, p. 81 Springer-Verlag Berlin Heidelberg 1996 Density functional theory of time-dependent phenomena E of density functional theory (DFT) is to describe an interacting many-particle system exclusively

Gross, E.K.U.

162

Density Functional Theory with Correct Long-Range Asymptotic Behavior Roi Baer1,* and Daniel Neuhauser2,  

E-Print Network [OSTI]

Density Functional Theory with Correct Long-Range Asymptotic Behavior Roi Baer1,* and Daniel within density functional theory (DFT) which spawns a class of approximations leading to correct long.043002 PACS numbers: 31.15.Ew, 31.15.Ne, 31.25.Eb, 71.15.Mb Density functional theory (DFT) [1,2] is an in

Baer, Roi

163

Electronic Structure: Density Functional Theory S. Kurth, M.A.L. Marques, and E. K. U. Gross  

E-Print Network [OSTI]

Electronic Structure: Density Functional Theory S. Kurth, M.A.L. Marques, and E. K. U. Gross: July 5, 2003) PACS numbers: 71.15.Mb, 31.15.Ew 1 #12; I. INTRODUCTION Density functional theory (DFT systems becomes prohibitive. A di#erent approach is taken in density functional theory where, instead

Gross, E.K.U.

164

High energy-density water: density functional theory calculations of structure and electrical conductivity.  

SciTech Connect (OSTI)

Knowledge of the properties of water is essential for correctly describing the physics of shock waves in water as well as the behavior of giant planets. By using finite temperature density functional theory (DFT), we have investigated the structure and electronic conductivity of water across three phase transitions (molecular liquid/ ionic liquid/super-ionic/electronic liquid). There is a rapid transition to ionic conduction at 2000 K and 2 g/cm{sup 3} while electronic conduction dominates at temperatures above 6000 K. We predict that the fluid bordering the super-ionic phase is conducting above 4000 K and 100 GPa. Earlier work instead has the super-ionic phase bordering an insulating fluid, with a transition to metallic fluid not until 7000 K and 250 GPa. The tools and expertise developed during the project can be applied to other molecular systems, for example, methane, ammonia, and CH foam. We are now well positioned to treat also complex molecular systems in the HEDP regime of phase-space.

Desjarlais, Michael Paul; Mattsson, Thomas Kjell Rene

2006-03-01T23:59:59.000Z

165

Magnetic and antimagnetic rotation in covariant density functional theory  

SciTech Connect (OSTI)

Progress on microscopic and self-consistent description of the magnetic rotation and antimagnetic rotation phenomena in tilted axis cranking relativistic mean-field theory based on a point-coupling interaction are briefly reviewed. In particular, the microscopic pictures of the shears mechanism in {sup 60}Ni and the two shears-like mechanism in {sup 105}Cd are discussed.

Zhao, P. W.; Liang, H. Z.; Peng, J.; Ring, P.; Zhang, S. Q.; Meng, J. [State Key Lab Nucl. Phys. and Tech., School of Physics, Peking University, Beijing 100871 (China); Department of Physics, Beijing Normal University, Beijing 100875 (China); State Key Lab Nucl. Phys. and Tech., School of Physics, Peking University, Beijing 100871 (China) and Physik Department, Technische Universitat Muenchen, D-85747 Garching (Germany); State Key Lab Nucl. Phys. and Tech., School of Physics, Peking University, Beijing 100871 (China); State Key Lab Nucl. Phys. and Tech., School of Physics, Peking University, Beijing 100871 (China) and Department of Physics, University of Stellenbosch, Stellenbosch (South Africa)

2012-10-20T23:59:59.000Z

166

Density Functional Theory in Surface Chemistry and Catalysis  

SciTech Connect (OSTI)

Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.

Norskov, Jens

2011-05-19T23:59:59.000Z

167

Molecular Density Functional Theory for water with liquid-gas coexistence and correct pressure  

E-Print Network [OSTI]

The solvation of hydrophobic solutes in water is special because liquid and gas are almost at coexistence. In the common hypernetted chain approximation to integral equations, or equivalently in the homogenous reference fluid of molecular density functional theory, coexistence is not taken into account. Hydration structures and energies of nanometer-scale hydrophobic solutes are thus incorrect. In this article, we propose a bridge functional that corrects this thermodynamic inconsistency by introducing a metastable gas phase for the homogeneous solvent. We show how this can be done by a third order expansion of the functional around the bulk liquid density that imposes the right pressure and the correct second order derivatives. Although this theory is not limited to water, we apply it to study hydrophobic solvation in water at room temperature and pressure and compare the results to all-atom simulations. With this correction, molecular density functional theory gives, at a modest computational cost, quantita...

Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel

2015-01-01T23:59:59.000Z

168

Nonequilibrium thermodynamics of interfaces using classical density functional theory  

E-Print Network [OSTI]

resistivities. The interfacial resistivities for heat transfer, for mass transfer, and for the coupling of heat and condensation.5,6 This description finds that the thermodynamic driving forces are linear functions of the heat the measurable heat fluxes differ on both sides. It is important to take the coupling between the heat and mass

Kjelstrup, Signe

169

On the existence of effective potentials in time-dependent density functional theory  

E-Print Network [OSTI]

We investigate the existence and properties of effective potentials in time-dependent density functional theory. We outline conditions for a general solution of the corresponding Sturm-Liouville boundary value problems. We define the set of potentials and v-representable densities, give a proof of existence of the effective potentials under certain restrictions, and show the set of v-representable densities to be independent of the interaction.

M. Ruggenthaler; M. Penz; D. Bauer

2009-11-10T23:59:59.000Z

170

Isospin coupling-channel decomposition of nuclear symmetry energy in covariant density functional theory  

E-Print Network [OSTI]

The isospin coupling-channel decomposition of the potential energy density functional is carried out within the covariant density functional theory, and their isospin and density dependence in particular the influence on the symmetry energy is studied. It is found that both isospin-singlet and isospin-triplet components of the potential energy play the dominant role in deciding the symmetry energy, especially when the Fock diagram is introduced. The results illustrate a quite different mechanism to the origin of the symmetry energy from the microscopic Brueckner-Hartree-Fock theory, and demonstrate the importance of the Fork diagram in the CDF theory, especially from the isoscalar mesons, in the isospin properties of the in-medium nuclear force at high density.

Qian Zhao; Bao Yuan Sun; Wen Hui Long

2014-11-23T23:59:59.000Z

171

Exact relations of the quasienergy functional and the exchange-correlation potential from the Floquet formulation of time-dependent density functional theory  

E-Print Network [OSTI]

the Floquet formulation of time-dependent density functional theory Dmitry A. Telnov and Shih-I Chu Department-dependent density functional theory we present several exact relations involving different parts of the quasienergy.012514 PACS number s : 71.45.Gm, 71.15.Mb, 31.15.Ew I. INTRODUCTION Time-independent density functional theory

Chu, Shih-I

172

Double-hybrid density-functional theory with meta-generalized-gradient approximations  

SciTech Connect (OSTI)

We extend the previously proposed one-parameter double-hybrid density-functional theory [K. Sharkas, J. Toulouse, and A. Savin, J. Chem. Phys. 134, 064113 (2011)] to meta-generalized-gradient-approximation (meta-GGA) exchange-correlation density functionals. We construct several variants of one-parameter double-hybrid approximations using the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional and test them on test sets of atomization energies and reaction barrier heights. The most accurate variant uses the uniform coordinate scaling of the density and of the kinetic energy density in the correlation functional, and improves over both standard Kohn-Sham TPSS and second-order Mller-Plesset calculations.

Souvi, Sidi M. O., E-mail: sidi.souvi@irsn.fr; Sharkas, Kamal; Toulouse, Julien, E-mail: julien.toulouse@upmc.fr [Sorbonne Universits, UPMC Univ Paris 06, UMR 7616, Laboratoire de Chimie Thorique, F-75005 Paris (France) [Sorbonne Universits, UPMC Univ Paris 06, UMR 7616, Laboratoire de Chimie Thorique, F-75005 Paris (France); CNRS, UMR 7616, Laboratoire de Chimie Thorique, F-75005 Paris (France)

2014-02-28T23:59:59.000Z

173

Density functional theory of freezing for soft interactions in two dimensions  

E-Print Network [OSTI]

A density functional theory of two-dimensional freezing is presented for a soft interaction potential that scales as inverse cube of particle distance. This repulsive potential between parallel, induced dipoles is realized for paramagnetic colloids on an interface, which are additionally exposed to an external magnetic field. An extended modified weighted density approximation which includes correct triplet correlations in the liquid state is used. The theoretical prediction of the freezing transition is in good agreement with experimental and simulation data.

Sven van Teeffelen; Christos N. Likos; Norman Hoffmann; Hartmut Lwen

2006-04-18T23:59:59.000Z

174

Structure of a liquid crystalline fluid around a macroparticle: Density functional theory study  

E-Print Network [OSTI]

The structure of a molecular liquid, in both the nematic liquid crystalline and isotropic phases, around a cylindrical macroparticle, is studied using density functional theory. In the nematic phase the structure of the fluid is highly anisotropic with respect to the director, in agreement with results from simulation and phenomenological theories. On going into the isotropic phase the structure becomes rotationally invariant around the macroparticle with an oriented layer at the surface.

David L. Cheung; Michael P. Allen

2006-04-10T23:59:59.000Z

175

Generalized dynamical density functional theory for classical fluids and the significance of inertia and hydrodynamic interactions  

E-Print Network [OSTI]

We study the dynamics of a colloidal fluid including inertia and hydrodynamic interactions, two effects which strongly influence the non-equilibrium properties of the system. We derive a general dynamical density functional theory (DDFT) which shows very good agreement with full Langevin dynamics. In suitable limits, we recover existing DDFTs and a Navier-Stokes-like equation with additional non-local terms.

Benjamin D. Goddard; Andreas Nold; Nikos Savva; Grigorios A. Pavliotis; Serafim Kalliadasis

2012-08-08T23:59:59.000Z

176

Density Functional Theory Studies of the Structure Sensitivity of Ethanol Oxidation on Palladium Surfaces  

E-Print Network [OSTI]

Density Functional Theory Studies of the Structure Sensitivity of Ethanol Oxidation on PalladiumVised Manuscript ReceiVed: May 04, 2010 In this work, the adsorption behaviors and oxidation mechanisms of ethanol palladium surfaces, the adsorption behaviors, and the first step dehydrogenation of ethanol, it is found

Zhao, Tianshou

177

Relativistic density functional theory modeling of plutonium and americium higher oxide molecules  

E-Print Network [OSTI]

Relativistic density functional theory modeling of plutonium and americium higher oxide molecules of plutonium and americium higher oxide molecules Andréi Zaitsevskii,1,2,a) Nikolai S. Mosyagin,2,3 Anatoly V of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two

Titov, Anatoly

178

Characterization of the nitrogen split interstitial defect in wurtzite aluminum nitride using density functional theory  

SciTech Connect (OSTI)

We carried out Heyd-Scuseria-Ernzerhof hybrid density functional theory plane wave supercell calculations in wurtzite aluminum nitride in order to characterize the geometry, formation energies, transition levels, and hyperfine tensors of the nitrogen split interstitial defect. The calculated hyperfine tensors may provide useful fingerprint of this defect for electron paramagnetic resonance measurement.

Szlls, A., E-mail: szallas.attila@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Szsz, K. [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Institute of Physics, Etvs University, Pzmny Pter stny 1/A, H-1117 Budapest (Hungary); Trinh, X. T.; Son, N. T.; Janzn, E. [Department of Physics, Chemistry and Biology, Linkping University, SE-581 83 Linkping (Sweden); Gali, A., E-mail: gali.adam@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki t 8, H-1111 Budapest (Hungary)

2014-09-21T23:59:59.000Z

179

Ultra-nonlocality in density functional theory for photo-emission spectroscopy  

SciTech Connect (OSTI)

We derive an exact expression for the photocurrent of photo-emission spectroscopy using time-dependent current density functional theory (TDCDFT). This expression is given as an integral over the Kohn-Sham spectral function renormalized by effective potentials that depend on the exchange-correlation kernel of current density functional theory. We analyze in detail the physical content of this expression by making a connection between the density-functional expression and the diagrammatic expansion of the photocurrent within many-body perturbation theory. We further demonstrate that the density functional expression does not provide us with information on the kinetic energy distribution of the photo-electrons. Such information can, in principle, be obtained from TDCDFT by exactly modeling the experiment in which the photocurrent is split into energy contributions by means of an external electromagnetic field outside the sample, as is done in standard detectors. We find, however, that this procedure produces very nonlocal correlations between the exchange-correlation fields in the sample and the detector.

Uimonen, A.-M. [Department of Physics, Nanoscience Center, University of Jyvskyl, Survontie 9, 40014 Jyvskyl (Finland)] [Department of Physics, Nanoscience Center, University of Jyvskyl, Survontie 9, 40014 Jyvskyl (Finland); Stefanucci, G. [Dipartimento di Fisica, Universit di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Rome (Italy) [Dipartimento di Fisica, Universit di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Rome (Italy); INFN, Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); European Theoretical Spectroscopy Facility (ETSF), Louvain-la Neuve (Belgium); Leeuwen, R. van [Department of Physics, Nanoscience Center, University of Jyvskyl, Survontie 9, 40014 Jyvskyl (Finland) [Department of Physics, Nanoscience Center, University of Jyvskyl, Survontie 9, 40014 Jyvskyl (Finland); European Theoretical Spectroscopy Facility (ETSF), Louvain-la Neuve (Belgium)

2014-05-14T23:59:59.000Z

180

Density functional theory for colloidal mixtures of hard platelets, rods, and spheres  

E-Print Network [OSTI]

A geometry-based density functional theory is presented for mixtures of hard spheres, hard needles and hard platelets; both the needles and the platelets are taken to be of vanishing thickness. Geometrical weight functions that are characteristic for each species are given and it is shown how convolutions of pairs of weight functions recover each Mayer bond of the ternary mixture and hence ensure the correct second virial expansion of the excess free energy functional. The case of sphere-platelet overlap relies on the same approximation as does Rosenfeld's functional for strictly two-dimensional hard disks. We explicitly control contributions to the excess free energy that are of third order in density. Analytic expressions relevant for the application of the theory to states with planar translational and cylindrical rotational symmetry, e.g. to describe behavior at planar smooth walls, are given. For binary sphere-platelet mixtures, in the appropriate limit of small platelet densities, the theory differs from that used in a recent treatment [L. Harnau and S. Dietrich, Phys. Rev. E 71, 011504 (2004)]. As a test case of our approach we consider the isotropic-nematic bulk transition of pure hard platelets, which we find to be weakly first order, with values for the coexistence densities and the nematic order parameter that compare well with simulation results.

Ansgar Esztermann; Hendrik Reich; Matthias Schmidt

2005-11-18T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Stability of titanium oxide phases in Kohn-Sham density functional A well known problem in practical Kohn-Sham (KS) density functional theory (DFT) calculations is that it yields the wrong order of  

E-Print Network [OSTI]

Stability of titanium oxide phases in Kohn-Sham density functional theory A well known problem in practical Kohn-Sham (KS) density functional theory (DFT) calculations is that it yields the wrong order-DFT, but with different levels of corrections to the exchange-correlation functional. Kohn-Sham density functional theory

Bjørnstad, Ottar Nordal

182

Dynamical density functional theory for the diffusion of injected Brownian particles  

E-Print Network [OSTI]

While the theory of diffusion of a single Brownian particle in confined geometries is well-established by now, we discuss here the theoretical framework necessary to generalize the theory of diffusion to dense suspensions of strongly interacting Brownian particles. Dynamical density functional theory (DDFT) for classical Brownian particles represents an ideal tool for this purpose. After outlining the basic ingredients to DDFT we show that it can be readily applied to flowing suspensions with time-dependent particle sources. Particle interactions lead to considerable layering in the mean density profiles, a feature that is absent in the trivial case of noninteracting, freely diffusing particles. If the particle injection rate varies periodically in time with a suitable frequency, a resonance in the layering of the mean particle density profile is predicted.

H. Lwen; M. Heinen

2014-09-08T23:59:59.000Z

183

Effective shell model Hamiltonians from density functional theory: quadrupolar and pairing correlations  

E-Print Network [OSTI]

We describe a procedure for mapping a self-consistent mean-field theory (also known as density functional theory) into a shell model Hamiltonian that includes quadrupole-quadrupole and monopole pairing interactions in a truncated space. We test our method in the deformed N=Z sd-shell nuclei Ne-20, Mg-24 and Ar-36, starting from the Hartree-Fock plus BCS approximation of the USD shell model interaction. A similar procedure is then followed using the SLy4 Skyrme energy density functional in the particle-hole channel plus a zero-range density-dependent force in the pairing channel. Using the ground-state solution of this density functional theory at the Hartree-Fock plus BCS level, an effective shell model Hamiltonian is constructed. We use this mapped Hamiltonian to extract quadrupolar and pairing correlation energies beyond the mean field approximation. The rescaling of the mass quadrupole operator in the truncated shell model space is found to be almost independent of the coupling strength used in the pairing channel of the underlying mean-field theory.

R. Rodriguez-Guzman; Y. Alhassid; G. F. Bertsch

2007-09-04T23:59:59.000Z

184

Density functional approaches to collective phenomena in nuclei: Time-dependent density-functional theory for perturbative and non-perturbative nuclear dynamics  

E-Print Network [OSTI]

We present the basic concepts and our recent developments in the density functional approaches with the Skyrme functionals for describing nuclear dynamics at low energy. The time-dependent density-functional theory (TDDFT) is utilized for the exact linear response with an external perturbation. For description of collective dynamics beyond the perturbative regime, we present a theory of a decoupled collective submanifold to describe for a slow motion based on the TDDFT. Selected applications are shown to demonstrate the quality of their performance and feasibility. Advantages and disadvantages in the numerical aspects are also discussed.

Takashi Nakatsukasa

2012-10-01T23:59:59.000Z

185

Density functional theory for hard-sphere mixtures: the White-Bear version Mark II  

E-Print Network [OSTI]

In the spirit of the White-Bear version of fundamental measure theory we derive a new density functional for hard-sphere mixtures which is based on a recent mixture extension of the Carnahan-Starling equation of state. In addition to the capability to predict inhomogeneous density distributions very accurately, like the original White-Bear version, the new functional improves upon consistency with an exact scaled-particle theory relation in the case of the pure fluid. We examine consistency in detail within the context of morphological thermodynamics. Interestingly, for the pure fluid the degree of consistency of the new version is not only higher than for the original White-Bear version but also higher than for Rosenfeld's original fundamental measure theory.

Hendrik Hansen-Goos; Roland Roth

2006-07-27T23:59:59.000Z

186

Computationally efficient double hybrid density functional theory using dual basis methods  

E-Print Network [OSTI]

We examine the application of the recently developed dual basis methods of Head-Gordon and co-workers to double hybrid density functional computations. Using the B2-PLYP, B2GP-PLYP, DSD-BLYP and DSD-PBEP86 density functionals, we assess the performance of dual basis methods for the calculation of conformational energy changes in C$_4$-C$_7$ alkanes and for the S22 set of noncovalent interaction energies. The dual basis methods, combined with resolution-of-the-identity second-order M{\\o}ller-Plesset theory, are shown to give results in excellent agreement with conventional methods at a much reduced computational cost.

Byrd, Jason N

2015-01-01T23:59:59.000Z

187

Effective electron displacements: A tool for time-dependent density functional theory computational spectroscopy  

SciTech Connect (OSTI)

We extend our previous definition of the metric ?r for electronic excitations in the framework of the time-dependent density functional theory [C. A. Guido, P. Cortona, B. Mennucci, and C. Adamo, J. Chem. Theory Comput. 9, 3118 (2013)], by including a measure of the difference of electronic position variances in passing from occupied to virtual orbitals. This new definition, called ?, permits applications in those situations where the ?r-index is not helpful: transitions in centrosymmetric systems and Rydberg excitations. The ?-metric is then extended by using the Natural Transition Orbitals, thus providing an intuitive picture of how locally the electron density changes during the electronic transitions. Furthermore, the ? values give insight about the functional performances in reproducing different type of transitions, and allow one to define a confidence radius for GGA and hybrid functionals.

Guido, Ciro A., E-mail: ciro.guido@ecp.fr; Cortona, Pietro [Laboratoire Structures, Proprits et Modlisation des Solides (SPMS), CNRS UMR 8580, cole Centrale Paris, Grande Voie des Vignes, F-92295 Chtenay-Malabry (France)] [Laboratoire Structures, Proprits et Modlisation des Solides (SPMS), CNRS UMR 8580, cole Centrale Paris, Grande Voie des Vignes, F-92295 Chtenay-Malabry (France); Adamo, Carlo [Laboratoire dlectrochimie, Chimie des Interfaces et Modlisation pour lEnergie, CNRS UMR-7575, Chimie ParisTech, 11 rue P. et M. Curie, F-75231 Paris Cedex 05 (France) [Laboratoire dlectrochimie, Chimie des Interfaces et Modlisation pour lEnergie, CNRS UMR-7575, Chimie ParisTech, 11 rue P. et M. Curie, F-75231 Paris Cedex 05 (France); Institut Universitaire de France, 103 Bd Saint-Michel, F-75005 Paris (France)

2014-03-14T23:59:59.000Z

188

On the contact values of the density profiles in an electric double layer using density functional theory  

E-Print Network [OSTI]

A recently proposed local second contact value theorem [Henderson D., Boda D., J. Electroanal. Chem., 2005, 582, 16] for the charge profile of an electric double layer is used in conjunction with the existing Monte Carlo data from the literature to assess the contact behavior of the electrode-ion distributions predicted by the density functional theory. The results for the contact values of the co- and counterion distributions and their product are obtained for the symmetric valency, restricted primitive model planar double layer for a range of electrolyte concentrations and temperatures. Overall, the theoretical results satisfy the second contact value theorem reasonably well, the agreement with the simulations being semi-quantitative or better. The product of the co- and counterion contact values as a function of the electrode surface charge density is qualitative with the simulations with increasing deviations at higher concentrations.

L. B. Bhuiyan; D. Henderson; S. Soko?owski

2012-07-13T23:59:59.000Z

189

Covariant density functional theory with two-phonon coupling in nuclei  

SciTech Connect (OSTI)

A full description of excited states within the framework of density functional theory requires energy dependent self energies. We present a new class of many-body models. It allows a parameter free description of the fragmentation of nuclear states induced by mode coupling of two-quasiparticle and two-phonon configurations. The method is applied for an investigation of low-lying dipole excitations in Sn isotopes with large neutron excess.

Ring, P.; Litvinova, E.; Tselyaev, V. [Physik Department, Technische Universitat Muenchen, D-85747 Garching (Germany) and State Key Lab Nucl. Phys. and Tech., School of Physics, Peking University, Beijing 100871 (China); GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Nuclear Physics Department, St. Petersburg State University, 198504 St. Petersburg (Russian Federation)

2012-10-20T23:59:59.000Z

190

Steam Reforming on Transition-metal Carbides from Density-functional Theory  

SciTech Connect (OSTI)

A screening study of the steam reforming reaction on clean and oxygen covered early transition-metal carbides surfaces is performed by means of density-functional theory calculations. It is found that carbides provide a wide spectrum of reactivities, from too reactive via suitable to too inert. Several molybdenum-based systems are identified as possible steam reforming catalysts. The findings suggest that carbides provide a playground for reactivity tuning, comparable to the one for pure metals.

Vojvodic, Aleksandra

2012-05-11T23:59:59.000Z

191

Orbital-free density functional theory of out-of-plane charge screening in graphene  

E-Print Network [OSTI]

We propose a density functional theory of Thomas-Fermi-Dirac-von Weizs\\"acker type to describe the response of a single layer of graphene resting on a dielectric substrate to a point charge or a collection of point charges some distance away from the layer. We formulate a variational setting in which the proposed energy functional admits minimizers, both in the case of free graphene layers and under back-gating. We further provide conditions under which those minimizers are unique and correspond to configurations consisting of inhomogeneous density profiles of charge carrier of only one type. The associated Euler-Lagrange equation for the charge density is also obtained, and uniqueness, regularity and decay of the minimizers are proved under general conditions. In addition, a bifurcation from zero to non-zero response at a finite threshold value of the external charge is proved.

Jianfeng Lu; Vitaly Moroz; Cyrill B. Muratov

2014-05-20T23:59:59.000Z

192

Real-time linear response for time-dependent density-functional theory Department of Physical Chemistry and the Lise Meitner Minerva-Center for Quantum Chemistry,  

E-Print Network [OSTI]

Real-time linear response for time-dependent density-functional theory Roi Baer Department a linear-response approach for time-dependent density-functional theories using time-adiabatic functionals ground state. This ground state can be treated using density-functional theory, where the density n0(r) 2

Baer, Roi

193

The importance of nonlinear fluid response in joint density-functional theory studies of battery systems  

E-Print Network [OSTI]

Delivering the full benefits of first principles calculations to battery materials demands the development of accurate and computationally-efficient electronic structure methods that incorporate the effects of the electrolyte environment and electrode potential. Realistic electrochemical interfaces containing polar surfaces are beyond the regime of validity of existing continuum solvation theories developed for molecules, due to the presence of significantly stronger electric fields. We present an ab initio theory of the nonlinear dielectric and ionic response of solvent environments within the framework of joint density-functional theory, with precisely the same optimizable parameters as conventional polarizable continuum models. We demonstrate that the resulting nonlinear theory agrees with the standard linear models for organic molecules and metallic surfaces under typical operating conditions. However, we find that the saturation effects in the rotational response of polar solvent molecules, inherent to o...

Gunceler, Deniz; Sundararaman, Ravishankar; Schwarz, Kathleen A; Arias, T A

2013-01-01T23:59:59.000Z

194

Bulk phase behaviour of binary hard platelet mixtures from density functional theory  

E-Print Network [OSTI]

We investigate isotropic-isotropic, isotropic-nematic and nematic-nematic phase coexistence in binary mixtures of circular platelets with vanishing thickness, continuous rotational degrees of freedom and radial size ratios $\\lambda$ up to 5. A fundamental measure density functional theory, previously used for the one-component model, is proposed and results are compared against those from Onsager theory as a benchmark. For $\\lambda \\leq 1.7$ the system displays isotropic-nematic phase coexistence with a widening of the biphasic region for increasing values of $\\lambda$. For size ratios $\\lambda \\geq 2$, we find demixing into two nematic states becomes stable and an isotropic-nematic-nematic triple point can occur. Fundamental measure theory gives a smaller isotropic-nematic biphasic region than Onsager theory and locates the transition at lower densities. Furthermore, nematic-nematic demixing occurs over a larger range of compositions at a given value of $\\lambda$ than found in Onsager theory. Both theories predict the same topologies of the phase diagrams. The partial nematic order parameters vary strongly with composition and indicate that the larger particles are more strongly ordered than the smaller particles.

Jonathan Phillips; Matthias Schmidt

2010-01-29T23:59:59.000Z

195

Double-hybrid density-functional theory applied to molecular crystals  

E-Print Network [OSTI]

We test the performance of a number of two- and one-parameter double-hybrid approximations, combining semilocal exchange-correlation density functionals with periodic local second-order M{\\o}ller-Plesset (LMP2) perturbation theory, for calculating lattice energies of a set of molecular crystals: urea, formamide, ammonia, and carbon dioxide. All double-hybrid methods perform better on average than the corresponding Kohn-Sham calculations with the same functionals, but generally not better than standard LMP2. The one-parameter double-hybrid approximations based on the PBEsol density functional gives lattice energies per molecule with an accuracy of about 6 kJ/mol, which is similar to the accuracy of LMP2. This conclusion is further verified on molecular dimers and on the hydrogen cyanide crystal.

Sharkas, Kamal; Maschio, Lorenzo; Civalleri, Bartolomeo

2014-01-01T23:59:59.000Z

196

Time-dependent density functional theory quantum transport simulation in non-orthogonal basis  

SciTech Connect (OSTI)

Basing on the earlier works on the hierarchical equations of motion for quantum transport, we present in this paper a first principles scheme for time-dependent quantum transport by combining time-dependent density functional theory (TDDFT) and Keldysh's non-equilibrium Green's function formalism. This scheme is beyond the wide band limit approximation and is directly applicable to the case of non-orthogonal basis without the need of basis transformation. The overlap between the basis in the lead and the device region is treated properly by including it in the self-energy and it can be shown that this approach is equivalent to a lead-device orthogonalization. This scheme has been implemented at both TDDFT and density functional tight-binding level. Simulation results are presented to demonstrate our method and comparison with wide band limit approximation is made. Finally, the sparsity of the matrices and computational complexity of this method are analyzed.

Kwok, Yan Ho; Xie, Hang; Yam, Chi Yung; Chen, Guan Hua, E-mail: ghc@everest.hku.hk [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong); Zheng, Xiao [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2013-12-14T23:59:59.000Z

197

Electronic density-of-states of amorphous vanadium pentoxide films: Electrochemical data and density functional theory calculations  

SciTech Connect (OSTI)

Thin films of V{sub 2}O{sub 5} were prepared by sputter deposition onto transparent and electrically conducting substrates and were found to be X-ray amorphous. Their electrochemical density of states was determined by chronopotentiometry and displayed a pronounced low-energy peak followed by an almost featureless contribution at higher energies. These results were compared with density functional theory calculations for amorphous V{sub 2}O{sub 5}. Significant similarities were found between measured data and computations; specifically, the experimental low-energy peak corresponds to a split-off part of the conduction band apparent in the computations. Furthermore, the calculations approximately reproduce the experimental band gap observed in optical measurements.

Lykissa, Iliana; Li, Shu-Yi; Granqvist, Claes G.; Niklasson, Gunnar A., E-mail: gunnar.niklasson@angstrom.uu.se [Department of Engineering Sciences, The ngstrm Laboratory, Uppsala University, P.O. Box 534, SE-75121 Uppsala (Sweden); Ramzan, Muhammad [Department of Physics and Astronomy, The ngstrm Laboratory, Uppsala University, P.O. Box 516, SE-75120 Uppsala (Sweden); Chakraborty, Sudip; Ahuja, Rajeev [Department of Physics and Astronomy, The ngstrm Laboratory, Uppsala University, P.O. Box 516, SE-75120 Uppsala (Sweden); Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), SE-100 44 Stockholm (Sweden)

2014-05-14T23:59:59.000Z

198

Testing time-dependent density functional theory with depopulated molecular orbitals for predicting electronic excitation energies of valence, Rydberg, and charge-transfer  

E-Print Network [OSTI]

Testing time-dependent density functional theory with depopulated molecular orbitals for predicting functionals for time-dependent density functional theory calculations of valence and Rydberg electronic functional that performs well for both ground-state properties and time-dependent density functional theory

Truhlar, Donald G

199

Coarse-grained spin density-functional theory: infinite-volume limit via the hyperfinite  

E-Print Network [OSTI]

Coarse-grained spin density functional theory (SDFT) is a version of SDFT which works with number/spin densities specified to a limited resolution --- averages over cells of a regular spatial partition --- and external potentials constant on the cells. This coarse-grained setting facilitates a rigorous investigation of the mathematical foundations which goes well beyond what is currently possible in the conventional formualation. Problems of existence, uniqueness and regularity of representing potentials in the coarse-grained SDFT setting are here studied using techniques of (Robinsonian) nonstandard analysis. Every density which is nowhere spin-saturated is V-representable, and the set of representing potentials is the functional derivative, in an appropriate generalized sense, of the Lieb interal energy functional. Quasi-continuity and closure properties of the set-valued representing potentials map are also established. The extent of possible non-uniqueness is similar to that found in non-rigorous studies of the conventional theory, namely non-uniqueness can occur for states of collinear magnetization which are eigenstates of $S_z$.

Paul E. Lammert

2015-02-09T23:59:59.000Z

200

Canonical density matrix perturbation theory  

E-Print Network [OSTI]

Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free energy ensembles in tight-binding, Hartree-Fock or Kohn-Sham density functional theory. The canonical density matrix perturbation theory can be used to calculate temperature dependent response properties from the coupled perturbed self-consistent field equations as in density functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large non-metallic materials and metals at high temperatures.

Niklasson, Anders M N; Rubensson, Emanuel H; Rudberg, Elias

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Electronic and structural properties of ultrathin tungsten nanowires and nanotubes by density functional theory calculation  

SciTech Connect (OSTI)

The simulated annealing basin-hopping method incorporating the penalty function was used to predict the lowest-energy structures for ultrathin tungsten nanowires and nanotubes of different sizes. These predicted structures indicate that tungsten one-dimensional structures at this small scale do not possess B.C.C. configuration as in bulk tungsten material. In order to analyze the relationship between multi-shell geometries and electronic transfer, the electronic and structural properties of tungsten wires and tubes including partial density of state and band structures which were determined and analyzed by quantum chemistry calculations. In addition, in order to understand the application feasibility of these nanowires and tubes on nano-devices such as field emitters or chemical catalysts, the electronic stability of these ultrathin tungsten nanowires was also investigated by density functional theory calculations.

Sun, Shih-Jye [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Lin, Ken-Huang; Li, Jia-Yun [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Ju, Shin-Pon, E-mail: jushin-pon@mail.nsysu.edu.tw [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

2014-10-07T23:59:59.000Z

202

Singlet-Triplet Energy Gaps for Diradicals from Fractional-Spin Density-Functional Theory  

SciTech Connect (OSTI)

Open-shell singlet diradicals are difficult to model accurately within conventional Kohn?Sham (KS) density-functional theory (DFT). These methods are hampered by spin contamination because the KS determinant wave function is neither a pure spin state nor an eigenfunction of the S2 operator. Here we present a theoretical foray for using single-reference closed-shell ground states to describe diradicals by fractional-spin DFT (FS-DFT). This approach allows direct, self-consistent calculation of electronic properties using the electron density corresponding to the proper spin eigenfunction. The resulting FS-DFT approach is benchmarked against diradical singlet?triplet gaps for atoms and small molecules. We have also applied FS-DFT to the singlet?triplet gaps of hydrocarbon polyacenes.

Ess, Daniel H.; Johnson, E R; Hu, Xiangqian; Yang, W T

2011-01-01T23:59:59.000Z

203

Uncertainty Quantification for Nuclear Density Functional Theory and Information Content of New Measurements  

E-Print Network [OSTI]

Statistical tools of uncertainty quantification can be used to assess the information content of measured observables with respect to present-day theoretical models; to estimate model errors and thereby improve predictive capability; to extrapolate beyond the regions reached by experiment; and to provide meaningful input to applications and planned measurements. To showcase new opportunities offered by such tools, we make a rigorous analysis of theoretical statistical uncertainties in nuclear density functional theory using Bayesian inference methods. By considering the recent mass measurements from the Canadian Penning Trap at Argonne National Laboratory, we demonstrate how the Bayesian analysis and a direct least-squares optimization, combined with high-performance computing, can be used to assess the information content of the new data with respect to a model based on the Skyrme energy density functional approach. Employing the posterior probability distribution computed with a Gaussian process emulator, w...

McDonnell, J D; Higdon, D; Sarich, J; Wild, S M; Nazarewicz, W

2015-01-01T23:59:59.000Z

204

van der Waals forces in density functional theory: The vdW-DF method  

E-Print Network [OSTI]

A density functional theory (DFT) that accounts for van der Waals (vdW) interactions in condensed matter, materials physics, chemistry, and biology is reviewed. The insights that led to the construction of the Rutgers-Chalmers van der Waals Density Functional (vdW-DF) are presented with the aim of giving a historical perspective, while also emphasising more recent efforts which have sought to improve its accuracy. In addition to technical details, we discuss a range of recent applications that illustrate the necessity of including dispersion interactions in DFT. This review highlights the value of the vdW-DF method as a general-purpose method, not only for dispersion bound systems, but also in densely packed systems where these types of interactions are traditionally thought to be negligible.

Berland, Kristian; Lee, Kyuho; Schrder, Elsebeth; Thonhauser, T; Hyldgaard, Per; Lundqvist, Bengt I

2014-01-01T23:59:59.000Z

205

Why do ultrasoft repulsive particles cluster and crystallize? Analytical results from density functional theory  

E-Print Network [OSTI]

We demonstrate the accuracy of the hypernetted chain closure and of the mean-field approximation for the calculation of the fluid-state properties of systems interacting by means of bounded and positive-definite pair potentials with oscillating Fourier transforms. Subsequently, we prove the validity of a bilinear, random-phase density functional for arbitrary inhomogeneous phases of the same systems. On the basis of this functional, we calculate analytically the freezing parameters of the latter. We demonstrate explicitly that the stable crystals feature a lattice constant that is independent of density and whose value is dictated by the position of the negative minimum of the Fourier transform of the pair potential. This property is equivalent with the existence of clusters, whose population scales proportionally to the density. We establish that regardless of the form of the interaction potential and of the location on the freezing line, all cluster crystals have a universal Lindemann ratio L = 0.189 at freezing. We further make an explicit link between the aforementioned density functional and the harmonic theory of crystals. This allows us to establish an equivalence between the emergence of clusters and the existence of negative Fourier components of the interaction potential. Finally, we make a connection between the class of models at hand and the system of infinite-dimensional hard spheres, when the limits of interaction steepness and space dimension are both taken to infinity in a particularly described fashion.

Christos N. Likos; Bianca M. Mladek; Dieter Gottwald; Gerhard Kahl

2007-02-22T23:59:59.000Z

206

Calculation of the Micellar Structure of Polymer Surfactant Based on the Density Functional Theory  

E-Print Network [OSTI]

Amphiphilic block copolymer solutions form various micellar structures including micelles and vesicles. We applied the density functional theory for block copolymers which we have proposed to amphiphilic block copolymer systems. The 3 dimensional simulation for AB diblock copolymer solutions and AB diblock copolymer / A homopolymer blends has been done and it is shown that the spherical micelles, cylindrical micelles and spherical vesicles are formed. It is also shown that the phase diagram for AB diblock copolymer / A homopolymer blends qualitatively agrees with the phase diagram obtained by the experiment.

Takashi Uneyama; Masao Doi

2005-04-26T23:59:59.000Z

207

Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems  

E-Print Network [OSTI]

We discuss the applicability of long-range separated density functional theory (DFT) to the prediction of electronic transitions of a particular photocatalytic system based on an Ir(III) photosensitizer (IrPS). Special attention is paid to the charge-transfer properties which are of key importance for the photoexcitation dynamics, but and cannot be correctly described by means of conventional DFT. The optimization of the range-separation parameter is discussed for IrPS including its complexes with electron donors and acceptors used in photocatalysis. Particular attention is paid to the problems arising for a description of medium effects by a polarizable continuum model.

Bokareva, Olga S; Bokarev, Sergey I; Khn, Oliver

2015-01-01T23:59:59.000Z

208

Growth mechanism of atomic layer deposition of zinc oxide: A density functional theory approach  

SciTech Connect (OSTI)

Atomic layer deposition of zinc oxide (ZnO) using diethylzinc (DEZ) and water is studied using density functional theory. The reaction pathways between the precursors and ZnO surface sites are discussed. Both reactions proceed by the formation of intermediate complexes on the surface. The Gibbs free energy of the formation of these complexes is positive at temperatures above ?120?C and ?200?C for DEZ and water half-reactions, respectively. Spectroscopic ellipsometry results show that the growth per cycle changes at approximately the same temperatures.

Afshar, Amir; Cadien, Kenneth C., E-mail: kcadien@ualberta.ca [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)

2013-12-16T23:59:59.000Z

209

Role of exchange in density-functional theory for weakly interacting systems: Quantum Monte Carlo analysis of electron density and interaction energy  

E-Print Network [OSTI]

We analyze the density-functional theory (DFT) description of weak interactions by employing diffusion and reptation quantum Monte Carlo (QMC) calculations, for a set of benzene-molecule complexes. While the binding energies ...

Grossman, Jeffrey C.

210

Localized form of Fock terms in nuclear covariant density functional theory  

E-Print Network [OSTI]

In most of the successful versions of covariant density functional theory in nuclei, the Fock terms are not included explicitly, which leads to local functionals and forms the basis of their widespread applicability at present. However, it has serious consequences for the description of Gamow-Teller resonances (GTR) and spin-dipole resonances (SDR) which can only be cured by adding further phenomenological parameters. Relativistic Hartree-Fock models do not suffer from these problems. They can successfully describe the GTR and SDR as well as the isovector part of the Dirac effective mass without any additional parameters. However, they are non-local and require considerable numerical efforts. By the zero-range reduction and the Fierz transformation, a new method is proposed to take into account the Fock terms in local functionals, which retains the simplicity of conventional models and provides proper descriptions of the spin-isospin channels and the Dirac masses.

Haozhao Liang; Pengwei Zhao; Peter Ring; Xavier Roca-Maza; Jie Meng

2012-07-26T23:59:59.000Z

211

Perspective: Fifty years of density-functional theory in chemical physics  

SciTech Connect (OSTI)

Since its formal inception in 19641965, Kohn-Sham density-functional theory (KS-DFT) has become the most popular electronic structure method in computational physics and chemistry. Its popularity stems from its beautifully simple conceptual framework and computational elegance. The rise of KS-DFT in chemical physics began in earnest in the mid 1980s, when crucial developments in its exchange-correlation term gave the theory predictive power competitive with well-developed wave-function methods. Today KS-DFT finds itself under increasing pressure to deliver higher and higher accuracy and to adapt to ever more challenging problems. If we are not mindful, however, these pressures may submerge the theory in the wave-function sea. KS-DFT might be lost. I am hopeful the Kohn-Sham philosophical, theoretical, and computational framework can be preserved. This Perspective outlines the history, basic concepts, and present status of KS-DFT in chemical physics, and offers suggestions for its future development.

Becke, Axel D., E-mail: axel.becke@dal.ca [Department of Chemistry, Dalhousie University, 6274 Coburg Rd., P.O. Box 15000, Halifax, Nova Scotia B3H 4R2 (Canada)

2014-05-14T23:59:59.000Z

212

G-centers in irradiated silicon revisited: A screened hybrid density functional theory approach  

SciTech Connect (OSTI)

Electronic structure calculations employing screened hybrid density functional theory are used to gain fundamental insight into the interaction of carbon interstitial (C{sub i}) and substitutional (C{sub s}) atoms forming the C{sub i}C{sub s} defect known as G-center in silicon (Si). The G-center is one of the most important radiation related defects in Czochralski grown Si. We systematically investigate the density of states and formation energy for different types of C{sub i}C{sub s} defects with respect to the Fermi energy for all possible charge states. Prevalence of the neutral state for the C-type defect is established.

Wang, H.; Schwingenschlgl, U., E-mail: Udo.Schwingenschlogl@kaust.edu.sa [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Chroneos, A., E-mail: Alex.Chroneos@open.ac.uk [Engineering and Innovation, The Open University, Milton Keynes MK7 6AA (United Kingdom); Department of Materials, Imperial College, London SW7 2AZ (United Kingdom); Londos, C. A.; Sgourou, E. N. [University of Athens, Solid State Physics Section, Panepistimiopolis Zografos, Athens 157 84 (Greece)

2014-05-14T23:59:59.000Z

213

Modifying the variational principle in the action integral functional derivation of time-dependent density functional theory  

E-Print Network [OSTI]

According to a recent paper by G. Vignale [Phys. Rev. A 77, 062511 (2008), arXiv:0803.2727], the problems arising in the original derivation of time-dependent density functional theory (TDDFT) based on the Runge-Gross (RG) action-integral functional (AIF) are due to an incorrect variational principle (VP). This argument and the proposed modification of the VP are critically analyzed. The more fundamental problem, though, is the indefiniteness of the RG AIF. In contrast to a widely held belief, that indefiniteness is not eliminated in the variational procedure, which unwittingly is corroborated by Vignale's initial point.

J. Schirmer

2010-10-20T23:59:59.000Z

214

Analytic cubic and quartic force fields using density-functional theory  

SciTech Connect (OSTI)

We present the first analytic implementation of cubic and quartic force constants at the level of KohnSham density-functional theory. The implementation is based on an open-ended formalism for the evaluation of energy derivatives in an atomic-orbital basis. The implementation relies on the availability of open-ended codes for evaluation of one- and two-electron integrals differentiated with respect to nuclear displacements as well as automatic differentiation of the exchangecorrelation kernels. We use generalized second-order vibrational perturbation theory to calculate the fundamental frequencies of methane, ethane, benzene, and aniline, comparing B3LYP, BLYP, and HartreeFock results. The HartreeFock anharmonic corrections agree well with the B3LYP corrections when calculated at the B3LYP geometry and from B3LYP normal coordinates, suggesting that the inclusion of electron correlation is not essential for the reliable calculation of cubic and quartic force constants.

Ringholm, Magnus; Gao, Bin; Thorvaldsen, Andreas J.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of TromsThe Arctic University of Norway, 9037 Troms (Norway)] [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of TromsThe Arctic University of Norway, 9037 Troms (Norway); Jonsson, Dan [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of TromsThe Arctic University of Norway, 9037 Troms (Norway) [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of TromsThe Arctic University of Norway, 9037 Troms (Norway); High Performance Computing Group, University of TromsThe Arctic University of Norway, 9037 Troms (Norway); Bast, Radovan [Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, S-10691 Stockholm, Sweden and PDC Center for High Performance Computing, Royal Institute of Technology, S-10044 Stockholm (Sweden)] [Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, S-10691 Stockholm, Sweden and PDC Center for High Performance Computing, Royal Institute of Technology, S-10044 Stockholm (Sweden); Ekstrm, Ulf; Helgaker, Trygve [Center for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo (Norway)] [Center for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo (Norway)

2014-01-21T23:59:59.000Z

215

Magnetic rotations in 198Pb and 199Pb within covariant density functional theory  

E-Print Network [OSTI]

Well-known examples of shears bands in the nuclei 198Pb and 199Pb are investigated within tilted axis cranking relativistic mean-field theory. Energy spectra, the relation between spin and rotational frequency, deformation parameters and reduced $M1$ and $E2$ transition probabilities are calculated. The results are in good agreement with available data and with calculations based on the phenomenological pairing plus-quadrupole-quadrupole tilted-axis cranking model. It is shown that covariant density functional theory provides a successful microscopic and fully self-consistent description of magnetic rotation in the Pb region showing the characteristic properties as the shears mechanism and relatively large B(M1) transitions decreasing with increasing spin.

L. F. Yu; P. W. Zhao; S. Q. Zhang; P. Ring; J. Meng

2012-02-28T23:59:59.000Z

216

Density functional theory and evolution algorithm calculations of elastic properties of AlON  

SciTech Connect (OSTI)

Different models for aluminum oxynitride (AlON) were calculated using density functional theory and optimized using an evolutionary algorithm. Evolutionary algorithm and density functional theory (DFT) calculations starting from several models of AlON with different Al or O vacancy locations and different positions for the N atoms relative to the vacancy were carried out. The results show that the constant anion model [McCauley et al., J. Eur. Ceram. Soc. 29(2), 223 (2009)] with a random distribution of N atoms not adjacent to the Al vacancy has the lowest energy configuration. The lowest energy structure is in a reasonable agreement with experimental X-ray diffraction spectra. The optimized structure of a 55 atom unit cell was used to construct 220 and 440 atom models for simulation cells using DFT with a Gaussian basis set. Cubic elastic constant predictions were found to approach the experimentally determined AlON single crystal elastic constants as the model size increased from 55 to 440 atoms. The pressure dependence of the elastic constants found from simulated stress-strain relations were in overall agreement with experimental measurements of polycrystalline and single crystal AlON. Calculated IR intensity and Raman spectra are compared with available experimental data.

Batyrev, I. G.; Taylor, D. E.; Gazonas, G. A.; McCauley, J. W. [U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States)

2014-01-14T23:59:59.000Z

217

Uncertainty Quantification for Nuclear Density Functional Theory and Information Content of New Measurements  

E-Print Network [OSTI]

Statistical tools of uncertainty quantification can be used to assess the information content of measured observables with respect to present-day theoretical models; to estimate model errors and thereby improve predictive capability; to extrapolate beyond the regions reached by experiment; and to provide meaningful input to applications and planned measurements. To showcase new opportunities offered by such tools, we make a rigorous analysis of theoretical statistical uncertainties in nuclear density functional theory using Bayesian inference methods. By considering the recent mass measurements from the Canadian Penning Trap at Argonne National Laboratory, we demonstrate how the Bayesian analysis and a direct least-squares optimization, combined with high-performance computing, can be used to assess the information content of the new data with respect to a model based on the Skyrme energy density functional approach. Employing the posterior probability distribution computed with a Gaussian process emulator, we apply the Bayesian framework to propagate theoretical statistical uncertainties in predictions of nuclear masses, two-neutron dripline, and fission barriers. Overall, we find that the new mass measurements do not impose a constraint that is strong enough to lead to significant changes in the model parameters. The example discussed in this study sets the stage for quantifying and maximizing the impact of new measurements with respect to current modeling and guiding future experimental efforts, thus enhancing the experiment-theory cycle in the scientific method.

J. D. McDonnell; N. Schunck; D. Higdon; J. Sarich; S. M. Wild; W. Nazarewicz

2015-01-15T23:59:59.000Z

218

A high-throughput infrastructure for density functional theory calculations Anubhav Jain, Geoffroy Hautier, Charles J. Moore, Shyue Ping Ong, Christopher C. Fischer,  

E-Print Network [OSTI]

A high-throughput infrastructure for density functional theory calculations Anubhav Jain, Geoffroy-throughput computation Density functional theory Materials screening GGA Formation enthalpies a b s t r a c t The use of high-throughput density functional theory (DFT) calculations to screen for new materials and conduct

Ceder, Gerbrand

219

1318 Brazilian Journal of Physics, vol. 36, no. 4A, December, 2006 A Bird's-Eye View of Density-Functional Theory  

E-Print Network [OSTI]

of the Brazilian Physical Society. It is an attempt to introduce density-functional theory (DFT) in a language of the many excellent more technical reviews available in the literature. Keywords: Density-functional theory of the Brazilian Physical So- ciety [1]. The main text is a description of density-functional theory (DFT

Wu, Zhigang

220

Thermally-assisted-occupation density functional theory with generalized-gradient approximations  

SciTech Connect (OSTI)

We extend the recently proposed thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] to generalized-gradient approximation (GGA) exchange-correlation density functionals. Relative to our previous TAO-LDA (i.e., the local density approximation to TAO-DFT), the resulting TAO-GGAs are significantly superior for a wide range of applications, such as thermochemistry, kinetics, and reaction energies. For noncovalent interactions, TAO-GGAs with empirical dispersion corrections are shown to yield excellent performance. Due to their computational efficiency for systems with strong static correlation effects, TAO-LDA and TAO-GGAs are applied to study the electronic properties (e.g., the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, and symmetrized von Neumann entropy) of acenes with different number of linearly fused benzene rings (up to 100), which is very challenging for conventional electronic structure methods. The ground states of acenes are shown to be singlets for all the chain lengths studied here. With the increase of acene length, the singlet-triplet energy gaps, vertical ionization potentials, and fundamental gaps decrease monotonically, while the vertical electron affinities and symmetrized von Neumann entropy (i.e., a measure of polyradical character) increase monotonically.

Chai, Jeng-Da, E-mail: jdchai@phys.ntu.edu.tw [Department of Physics, Center for Theoretical Sciences, and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)] [Department of Physics, Center for Theoretical Sciences, and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2014-05-14T23:59:59.000Z

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221

Fragment Approach to Constrained Density Functional Theory Calculations using Daubechies Wavelets  

E-Print Network [OSTI]

In a recent paper we presented a linear scaling Kohn-Sham density functional theory (DFT) code based on Daubechies wavelets, where a minimal set of localized support functions is optimized in situ and therefore adapted to the chemical properties of the molecular system. Thanks to the systematically controllable accuracy of the underlying basis set, this approach is able to provide an optimal contracted basis for a given system: accuracies for ground state energies and atomic forces are of the same quality as an uncontracted, cubic scaling approach. This basis set offers, by construction, a natural subset where the density matrix of the system can be projected. In this paper we demonstrate the flexibility of this minimal basis formalism in providing a basis set that can be reused as-is, i.e. without reoptimization, for charge-constrained DFT calculations within a fragment approach. Support functions, represented in the underlying wavelet grid, of the template fragments are roto-translated with high numerical p...

Ratcliff, Laura E; Mohr, Stephan; Deutsch, Thierry

2015-01-01T23:59:59.000Z

222

Accurate and systematically improvable density functional theory embedding for correlated wavefunctions  

SciTech Connect (OSTI)

We analyze the sources of error in quantum embedding calculations in which an active subsystem is treated using wavefunction methods, and the remainder using density functional theory. We show that the embedding potential felt by the electrons in the active subsystem makes only a small contribution to the error of the method, whereas the error in the nonadditive exchange-correlation energy dominates. We test an MP2 correction for this term and demonstrate that the corrected embedding scheme accurately reproduces wavefunction calculations for a series of chemical reactions. Our projector-based embedding method uses localized occupied orbitals to partition the system; as with other local correlation methods, abrupt changes in the character of the localized orbitals along a reaction coordinate can lead to discontinuities in the embedded energy, but we show that these discontinuities are small and can be systematically reduced by increasing the size of the active region. Convergence of reaction energies with respect to the size of the active subsystem is shown to be rapid for all cases where the density functional treatment is able to capture the polarization of the environment, even in conjugated systems, and even when the partition cuts across a double bond.

Goodpaster, Jason D.; Barnes, Taylor A.; Miller, Thomas F., E-mail: tfm@caltech.edu [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); Manby, Frederick R., E-mail: fred.manby@bristol.ac.uk [Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 ITS (United Kingdom)

2014-05-14T23:59:59.000Z

223

Global Minimum Determination of the Born-Oppenheimer Surface within Density Functional Theory  

SciTech Connect (OSTI)

We present a novel method, which we refer to as the dual minima hopping method, that allows us to find the global minimum of the potential energy surface (PES) within density functional theory for systems where a fast but less accurate calculation of the PES is possible. This method can rapidly find the ground state configuration of clusters and other complex systems with present day computer power by performing a systematic search. We apply the new method to silicon clusters. Even though these systems have already been extensively studied by other methods, we find new global minimum candidates for Si{sub 16} and Si{sub 19}, as well as new low-lying isomers for Si{sub 16}, Si{sub 17}, and Si{sub 18}.

Goedecker, Stefan; Hellmann, Waldemar; Lenosky, Thomas [Institut fuer Physik, Universitaet Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Physics Department, Ohio State University, 1040 Physics Research Building, 191 West Woodruff Avenue, Columbus, Ohio 43210-1117 (United States)

2005-07-29T23:59:59.000Z

224

Fast plane wave density functional theory molecular dynamics calculations on multi-GPU machines  

SciTech Connect (OSTI)

Plane wave pseudopotential (PWP) density functional theory (DFT) calculation is the most widely used method for material simulations, but its absolute speed stagnated due to the inability to use large scale CPU based computers. By a drastic redesign of the algorithm, and moving all the major computation parts into GPU, we have reached a speed of 12 s per molecular dynamics (MD) step for a 512 atom system using 256 GPU cards. This is about 20 times faster than the CPU version of the code regardless of the number of CPU cores used. Our tests and analysis on different GPU platforms and configurations shed lights on the optimal GPU deployments for PWP-DFT calculations. An 1800 step MD simulation is used to study the liquid phase properties of GaInP.

Jia, Weile, E-mail: jiawl@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China) [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China); Fu, Jiyun, E-mail: fujy@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China) [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China); Cao, Zongyan, E-mail: zycao@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Wang, Long, E-mail: wangl@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Chi, Xuebin, E-mail: chi@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Gao, Weiguo, E-mail: wggao@fudan.edu.cn [School of Mathematical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 (China) [School of Mathematical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 (China); MOE Key Laboratory of Computational Physical Sciences, Fudan University, Shanghai (China); Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Material Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road Mail Stop 50F Berkeley, CA 94720 (United States)] [Material Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road Mail Stop 50F Berkeley, CA 94720 (United States)

2013-10-15T23:59:59.000Z

225

Analytical Energy Gradients in Range-Separated Hybrid Density Functional Theory with Random Phase Approximation  

E-Print Network [OSTI]

Analytical forces have been derived in the Lagrangian framework for several random phase approximation (RPA) correlated total energy methods based on the range separated hybrid (RSH) approach, which combines a short-range density functional approximation for the short-range exchange-correlation energy with a Hartree-Fock-type long-range exchange and RPA long-range correlation. The RPA correlation energy has been expressed as a ring coupled cluster doubles (rCCD) theory. The resulting analytical gradients have been implemented and tested for geometry optimization of simple molecules and intermolecular charge transfer complexes, where intermolecular interactions are expected to have a non-negligible effect even on geometrical parameters of the monomers.

Mussard, Bastien; ngyn, Jnos G

2015-01-01T23:59:59.000Z

226

Octupole deformation and Ra puzzle in reflection asymmetric covariant density functional theory  

E-Print Network [OSTI]

Reflection asymmetric covariant density functional theory(CDFT) based on the point-coupling interaction is established on a two-center harmonic-oscillator basis and applied to investigate the Ra puzzle, i.e., the anomalous enhancement of the residual proton-neutron interactions for Ra isotopes around N=135. The octupole deformation and shape evolution in the Ra and Rn isotopes are examined in the potential energy surfaces in(beta2, beta3) plane by the constrained reflection asymmetric calculations. The residual proton-neutron interactions extracted from the double difference of the binding energies for Ra isotopes are compared with the data as well as the axial and the triaxial calculations. It is found that the octupole deformation is responsible for the Ra puzzle in the microscopic CDFT.

L. F. Yu; P. W. Zhao; S. Q. Zhang; J. Meng

2012-11-03T23:59:59.000Z

227

Investigation of oxygen point defects in cubic ZrO2 by density functional theory  

SciTech Connect (OSTI)

The energetics of formation and migration of the oxygen vacancy and interstitial in cubic ZrO2 are investigated by density functional theory calculations. In an O-rich environment, the negatively charged oxygen interstitial is the most dominant defect whereas, the positively charged oxygen vacancy is the most dominant defect under O-poor conditions. Oxygen interstitial migration occurs by the interstitialcy and the direct interstitial mechanisms, with calculated migration energy barriers of 2.94 eV and 2.15 eV, respectively. For the oxygen vacancy, diffusion is preferred along the <100> direction, and the calculated energy barriers are 0.26 eV for , 0.27 eV for and 0.54 eV for . These results indicate that oxygen diffusivity is higher through the vacancy-migration mechanism.

Liu, Bin [ORNL] [ORNL; Xiao, Haiyan [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Zhang, Yanwen [ORNL] [ORNL; Aidhy, Dilpuneet S [ORNL] [ORNL; Weber, William J [ORNL] [ORNL

2014-01-01T23:59:59.000Z

228

Nuclear matrix elements in neutrinoless double beta decay: beyond mean-field covariant density functional theory  

E-Print Network [OSTI]

We report a systematic study of nuclear matrix elements (NMEs) in neutrinoless double-beta decays with state-of-the-art beyond mean-field covariant density functional theory. The dynamic effects of particle-number and angular-momentum conservations as well as quadrupole shape fluctuations are taken into account with projections and generator coordinate method for both initial and final nuclei. The full relativistic transition operator is adopted to calculate the NMEs which are found to be consistent with the results of previous beyond non-relativistic mean-field calculation based on a Gogny force with the exception of $^{150}$Nd. Our study shows that the total NMEs can be well approximated by the pure axial-vector coupling term, the calculation of which is computationally much cheaper than that of full terms.

J. M. Yao; L. S. Song; K. Hagino; P. Ring; J. Meng

2014-10-23T23:59:59.000Z

229

Nuclear matrix elements in neutrinoless double beta decay: beyond mean-field covariant density functional theory  

E-Print Network [OSTI]

We report a systematic study of nuclear matrix elements (NMEs) in neutrinoless double-beta decays with state-of-the-art beyond mean-field covariant density functional theory. The dynamic effects of particle-number and angular-momentum conservations as well as quadrupole shape fluctuations are taken into account with projections and generator coordinate method for both initial and final nuclei. The full relativistic transition operator is adopted to calculate the NMEs which are found to be consistent with the results of previous beyond non-relativistic mean-field calculation based on a Gogny force with the exception of $^{150}$Nd. Our study shows that the total NMEs can be well approximated by the pure axial-vector coupling term, the calculation of which is computationally much cheaper than that of full terms.

Yao, J M; Hagino, K; Ring, P; Meng, J

2014-01-01T23:59:59.000Z

230

Steam reforming on transition-metal carbides from density-functional theory  

E-Print Network [OSTI]

A screening study of the steam reforming reaction (CH_4 + H_2O -> CO + 3H_2) on early transition-metal carbides (TMC's) is performed by means of density-functional theory calculations. The set of considered surfaces includes the alpha-Mo_2C(100) surfaces, the low-index (111) and (100) surfaces of TiC, VC, and delta-MoC, and the oxygenated alpha-Mo_2C(100) and TMC(111) surfaces. It is found that carbides provide a wide spectrum of reactivities towards the steam reforming reaction, from too reactive via suitable to too inert. The reactivity is discussed in terms of the electronic structure of the clean surfaces. Two surfaces, the delta-MoC(100) and the oxygen passivated alpha-Mo_2C(100) surfaces, are identified as promising steam reforming catalysts. These findings suggest that carbides provide a playground for reactivity tuning, comparable to the one for pure metals.

Vojvodic, Aleksandra

2009-01-01T23:59:59.000Z

231

Integrating Experiment and Theory in Electrochemical Surface Science: Studies on the Molecular Adsorption on Noble-Metal Electrode Surfaces by Density Functional Theory, Electron Spectroscopy, and Electrochemistry  

E-Print Network [OSTI]

Computational techniques based on density functional theory (DFT) and experimental methods based on electrochemistry (EC), electrochemical scanning tunneling microscopy (EC-STM), and high-resolution electron energy loss spectroscopy (HREELS) were...

Javier, Alnald Caintic

2013-08-05T23:59:59.000Z

232

Energy level alignment and quantum conductance of functionalized metal-molecule junctions: Density functional theory versus GW calculations  

SciTech Connect (OSTI)

We study the effect of functional groups (CH{sub 3}*4, OCH{sub 3}, CH{sub 3}, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+?), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, ?, can bring the DFT conductances close to experiments, but does not improve on the relative ordering. We ascribe this to a too strong pinning of the molecular energy levels to the metal Fermi level by DFT which suppresses the variation in orbital energy with functional group.

Jin, Chengjun; Markussen, Troels; Thygesen, Kristian S., E-mail: thygesen@fysik.dtu.dk [Center for Atomic-scale Materials Design, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Strange, Mikkel; Solomon, Gemma C. [Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)] [Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark)

2013-11-14T23:59:59.000Z

233

Supplemental Material for Angular Momentum Dependent Orbital Free Density Functional Theory  

E-Print Network [OSTI]

)-(2) the general total energy functional of OFDFT can be rewritten as EOF [(r)] = EOF [{NR}, I(r)], (3) where introduce a smooth scaling function f(r) in the energy density of Ts - TKEDF s to make the KE density for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, USA 2 Material Science

Florian, Libisch

234

Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles  

E-Print Network [OSTI]

We present a theoretical model for the description of the adsorption kinetics of globular proteins onto charged core-shell microgel particles based on Dynamic Density Functional Theory (DDFT). This model builds on a previous description of protein adsorption thermodynamics [Yigit \\textit{et al}, Langmuir 28 (2012)], shown to well interpret the available calorimetric experimental data of binding isotherms. In practice, a spatially-dependent free-energy functional including the same physical interactions is built, and used to study the kinetics via a generalised diffusion equation. To test this model, we apply it to the case study of Lysozyme adsorption on PNIPAM coated nanoparticles, and show that the dynamics obtained within DDFT is consistent with that extrapolated from experiments. We also perform a systematic study of the effect of various parameters in our model, and investigate the loading dynamics as a function of proteins' valence and hydrophobic adsorption energy, as well as their concentration and that of the nanoparticles. Although we concentrated here on the case of adsorption for a single protein type, the model's generality allows to study multi-component system, providing a reliable instrument for future studies of competitive and cooperative adsorption effects often encountered in protein adsorption experiments.

Stefano Angioletti-Uberti; Matthias Ballauff; Joachim Dzubiella

2014-07-30T23:59:59.000Z

235

Density functional theory approach to gold-ligand interactions: Separating true effects from artifacts  

SciTech Connect (OSTI)

Donor-acceptor interactions are notoriously difficult and unpredictable for conventional density functional theory (DFT) methodologies. This work presents a reliable computational treatment of gold-ligand interactions of the donor-acceptor type within DFT. These interactions require a proper account of the ionization potential of the electron donor and electron affinity of the electron acceptor. This is accomplished in the Generalized Kohn Sham framework that allows one to relate these properties to the frontier orbitals in DFT via the tuning of range-separated functionals. A donor and an acceptor typically require different tuning schemes. This poses a problem when the binding energies are calculated using the supermolecular method. A two-parameter tuning for the monomer properties ensures that a common functional, optimal for both the donor and the acceptor, is found. A reliable DFT approach for these interactions also takes into account the dispersion contribution. The approach is validated using the water dimer and the (HAuPH{sub 3}){sub 2} aurophilic complex. Binding energies are computed for Au{sub 4} interacting with the following ligands: SCN{sup ?}, benzenethiol, benzenethiolate anion, pyridine, and trimethylphosphine. The results agree for the right reasons with coupled-cluster reference values.

Koppen, Jessica V.; Szcz??niak, Ma?gorzata M., E-mail: bryant@oakland.edu [Department of Chemistry, Oakland University, Rochester, Michigan 48309 (United States); Hapka, Micha?; Modrzejewski, Marcin [Faculty of Chemistry, Warsaw University, Pasteura 1, 02-093 Warszawa (Poland); Cha?asi?ski, Grzegorz [Faculty of Chemistry, Warsaw University, Pasteura 1, 02-093 Warszawa (Poland); Department of Chemistry, Oakland University, Rochester, Michigan 48309 (United States)

2014-06-28T23:59:59.000Z

236

Computational Complexity of interacting electrons and fundamental limitations of Density Functional Theory  

E-Print Network [OSTI]

One of the central problems in quantum mechanics is to determine the ground state properties of a system of electrons interacting via the Coulomb potential. Since its introduction by Hohenberg, Kohn, and Sham, Density Functional Theory (DFT) has become the most widely used and successful method for simulating systems of interacting electrons, making their original work one of the most cited in physics. In this letter, we show that the field of computational complexity imposes fundamental limitations on DFT, as an efficient description of the associated universal functional would allow to solve any problem in the class QMA (the quantum version of NP) and thus particularly any problem in NP in polynomial time. This follows from the fact that finding the ground state energy of the Hubbard model in an external magnetic field is a hard problem even for a quantum computer, while given the universal functional it can be computed efficiently using DFT. This provides a clear illustration how the field of quantum computing is useful even if quantum computers would never be built.

Norbert Schuch; Frank Verstraete

2010-09-27T23:59:59.000Z

237

Complex-energy approach to sum rules within nuclear density functional theory  

E-Print Network [OSTI]

The linear response of the nucleus to an external field contains unique information about the effective interaction, correlations, and properties of its excited states. To characterize the response, it is useful to use its energy-weighted moments, or sum rules. By comparing computed sum rules with experimental values, the information content of the response can be utilized in the optimization process of the nuclear Hamiltonian or EDF. But the additional information comes at a price: compared to the ground state, computation of excited states is more demanding. To establish an efficient framework to compute sum rules of the response that is adaptable to the optimization of the nuclear EDF and large-scale surveys of collective strength, we have developed a new technique within the complex-energy FAM based on the QRPA. To compute sum rules, we carry out contour integration of the response function in the complex-energy plane. We benchmark our results against the conventional matrix formulation of the QRPA theory, the Thouless theorem for the energy-weighted sum rule, and the dielectric theorem for the inverse energy-weighted sum rule. We demonstrate that calculated sum-rule values agree with those obtained from the matrix formulation of the QRPA. We also discuss the applicability of both the Thouless theorem about the energy-weighted sum rule and the dielectric theorem for the inverse energy-weighted sum rule to nuclear density functional theory in cases when the EDF is not based on a Hamiltonian. The proposed sum-rule technique based on the complex-energy FAM is a tool of choice when optimizing effective interactions or energy functionals. The method is very efficient and well-adaptable to parallel computing. The FAM formulation is especially useful when standard theorems based on commutation relations involving the nuclear Hamiltonian and external field cannot be used.

Nobuo Hinohara; Markus Kortelainen; Witold Nazarewicz; Erik Olsen

2015-01-28T23:59:59.000Z

238

Radical Coupling Reactions in Lignin Synthesis: A Density Functional Theory Study  

SciTech Connect (OSTI)

Lignin is a complex, heterogeneous polymer in plant cell walls that provides mechanical strength to the plant stem and confers resistance to degrading microbes, enzymes, and chemicals. Lignin synthesis initiates through oxidative radical-radical coupling of monolignols, the most common of which are p-coumaryl, coniferyl, and sinapyl alcohols. Here, we use density functional theory to characterize radical-radical coupling reactions involved in monolignol dimerization. We compute reaction enthalpies for the initial self- and cross-coupling reactions of these monolignol radicals to form dimeric intermediates via six major linkages observed in natural lignin. The 8-O-4, 8-8, and 8-5 coupling are computed to be the most favorable, whereas the 5-O-4, 5-5, and 8-1 linkages are less favorable. Overall, p-coumaryl self- and cross-coupling reactions are calculated to be the most favorable. For cross-coupling reactions, in which each radical can couple via either of the two sites involved in dimer formation, the more reactive of the two radicals is found to undergo coupling at its site with the highest spin density.

Sangha, A. K.; Parks, J. M.; Standaert, R. F.; Ziebell, A.; Davis, M.; Smith, J. C.

2012-04-26T23:59:59.000Z

239

Describing long-range charge-separation processes with subsystem density-functional theory  

SciTech Connect (OSTI)

Long-range charge-transfer processes in extended systems are difficult to describe with quantum chemical methods. In particular, cost-effective (non-hybrid) approximations within time-dependent density functional theory (DFT) are not applicable unless special precautions are taken. Here, we show that the efficient subsystem DFT can be employed as a constrained DFT variant to describe the energetics of long-range charge-separation processes. A formal analysis of the energy components in subsystem DFT for such excitation energies is presented, which demonstrates that both the distance dependence and the long-range limit are correctly described. In addition, electronic couplings for these processes as needed for rate constants in Marcus theory can be obtained from this method. It is shown that the electronic structure of charge-separated states constructed by a positively charged subsystem interacting with a negatively charged one is difficult to converge charge leaking from the negative subsystem to the positive one can occur. This problem is related to the delocalization error in DFT and can be overcome with asymptotically correct exchangecorrelation (XC) potentials or XC potentials including a sufficiently large amount of exact exchange. We also outline an approximate way to obtain charge-transfer couplings between locally excited and charge-separated states.

Solovyeva, Alisa; Neugebauer, Johannes, E-mail: j.neugebauer@uni-muenster.de [Theoretische Organische Chemie, Organisch-Chemisches Institut and Center for Multiscale Theory and Simulation, Westflische Wilhelms-Universitt Mnster, Corrensstrae 40, 48149 Mnster (Germany)] [Theoretische Organische Chemie, Organisch-Chemisches Institut and Center for Multiscale Theory and Simulation, Westflische Wilhelms-Universitt Mnster, Corrensstrae 40, 48149 Mnster (Germany); Pavanello, Michele, E-mail: m.pavanello@rutgers.edu [Department of Chemistry, Rutgers University, 73 Warren St., Newark, New Jersey 07102 (United States)] [Department of Chemistry, Rutgers University, 73 Warren St., Newark, New Jersey 07102 (United States)

2014-04-28T23:59:59.000Z

240

Enantioselectivity of (321) chiral noble metal surfaces: A density functional theory study of lactate adsorption  

SciTech Connect (OSTI)

The adsorption of the chiral molecule lactate on the intrinsically chiral noble metal surfaces Pt(321), Au(321), and Ag(321) is studied by density functional theory calculations. We use the oPBE-vdW functional which includes van der Waals forces on an ab initio level. It is shown that the molecule binds via its carboxyl and the hydroxyl oxygen atoms to the surface. The binding energy is larger on Pt(321) and Ag(321) than on Au(321). An analysis of the contributions to the binding energy of the different molecular functional groups reveals that the deprotonated carboxyl group contributes most to the binding energy, with a much smaller contribution of the hydroxyl group. The Pt(321) surface shows considerable enantioselectivity of 0.06 eV. On Au(321) and Ag(321) it is much smaller if not vanishing. The chiral selectivity of the Pt(321) surface can be explained by two factors. First, it derives from the difference in van der Waals attraction of L- and D-lactate to the surface that we trace to differences in the binding energy of the methyl group. Second, the multi-point binding pattern for lactate on the Pt(321) surface is sterically more sensitive to surface chirality and also leads to large binding energy contributions of the hydroxyl group. We also calculate the charge transfer to the molecule and the work function to gauge changes in electronic structure of the adsorbed molecule. The work function is lowered by 0.8 eV on Pt(321) with much smaller changes on Au(321) and Ag(321)

Franke, J.-H. [Department of Physics, Campus Plaine, CP 231, Universite Libre de Bruxelles, 1050 Brussels (Belgium)] [Department of Physics, Campus Plaine, CP 231, Universite Libre de Bruxelles, 1050 Brussels (Belgium); Kosov, D. S. [School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4811 (Australia)] [School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4811 (Australia)

2013-12-14T23:59:59.000Z

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241

Communication: Self-interaction correction with unitary invariance in density functional theory  

SciTech Connect (OSTI)

Standard spin-density functionals for the exchange-correlation energy of a many-electron ground state make serious self-interaction errors which can be corrected by the Perdew-Zunger self-interaction correction (SIC). We propose a size-extensive construction of SIC orbitals which, unlike earlier constructions, makes SIC computationally efficient, and a true spin-density functional. The SIC orbitals are constructed from a unitary transformation that is explicitly dependent on the non-interacting one-particle density matrix. When this SIC is applied to the local spin-density approximation, improvements are found for the atomization energies of molecules.

Pederson, Mark R., E-mail: mark.pederson@science.doe.gov [Office of Basic Energy Sciences, SC22.1, U.S. Department of Energy, Washington, DC 20585 (United States); Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Ruzsinszky, Adrienn [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States)] [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Perdew, John P. [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States) [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)

2014-03-28T23:59:59.000Z

242

Hardness of FeB{sub 4}: Density functional theory investigation  

SciTech Connect (OSTI)

A recent experimental study reported the successful synthesis of an orthorhombic FeB{sub 4} with a high hardness of 62(5) GPa [H. Gou et al., Phys. Rev. Lett. 111, 157002 (2013)], which has reignited extensive interests on whether transition-metal borides compounds will become superhard materials. However, it is contradicted with some theoretical studies suggesting transition-metal boron compounds are unlikely to become superhard materials. Here, we examined structural and electronic properties of FeB{sub 4} using density functional theory. The electronic calculations show the good metallicity and covalent FeB bonding. Meanwhile, we extensively investigated stress-strain relations of FeB{sub 4} under various tensile and shear loading directions. The calculated weakest tensile and shear stresses are 40 GPa and 25 GPa, respectively. Further simulations (e.g., electron localization function and bond length along the weakest loading direction) on FeB{sub 4} show the weak FeB bonding is responsible for this low hardness. Moreover, these results are consistent with the value of Vickers hardness (11.732.3 GPa) by employing different empirical hardness models and below the superhardness threshold of 40 GPa. Our current results suggest FeB{sub 4} is a hard material and unlikely to become superhard (>40 GPa)

Zhang, Miao; Du, Yonghui; Gao, Lili [Department of Physics, Beihua University, Jilin 132013 (China)] [Department of Physics, Beihua University, Jilin 132013 (China); Lu, Mingchun [Department of Aeronautical Engineering Professional Technology, Jilin Institute of Chemical Technology, Jilin 132102 (China)] [Department of Aeronautical Engineering Professional Technology, Jilin Institute of Chemical Technology, Jilin 132102 (China); Lu, Cheng [Department of Physics, Nanyang Normal University, Nanyang 473061 (China)] [Department of Physics, Nanyang Normal University, Nanyang 473061 (China); Liu, Hanyu, E-mail: hal420@mail.usask.ca [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada)] [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada)

2014-05-07T23:59:59.000Z

243

Density-Functional-Theory Calculations of Matter in Strong Magnetic Fields: I. Atoms and Molecules  

E-Print Network [OSTI]

We present new ab initio calculations of the electronic structure of various atoms and molecules in strong magnetic fields ranging from B=10^12 G to 2x10^15 G, appropriate for radio pulsars and magnetars. For these field strengths, the magnetic forces on the electrons dominate over the Coulomb forces, and to a good approximation the electrons are confined to the ground Landau level. Our calculations are based on the density functional theory, and use a local magnetic exchange-correlation function which is tested to be reliable in the strong field regime. Numerical results of the ground-state energies are given for H_N (up to N=10), He_N (up to N=8), C_N (up to N=5) and Fe_N (up to N=3), as well as for various ionized atoms. Fitting formulae for the B-dependence of the energies are also given. In general, as N increases, the binding energy per atom in a molecule, |E_N|/N, increases and approaches a constant value. For all the field strengths considered in this paper, hydrogen, helium, and carbon molecules are found to be bound relative to individual atoms (although for B less than a few x 10^12 G, the relative binding between C and C_2 is small). Iron molecules are not bound at B<10^13 G, but become energetically more favorable than individual atoms at larger field strengths.

Zach Medin; Dong Lai

2007-01-05T23:59:59.000Z

244

Using the electron localization function to correct for confinement physics in semi-local density functional theory  

SciTech Connect (OSTI)

We have previously proposed that further improved functionals for density functional theory can be constructed based on the Armiento-Mattsson subsystem functional scheme if, in addition to the uniform electron gas and surface models used in the Armiento-Mattsson 2005 functional, a model for the strongly confined electron gas is also added. However, of central importance for this scheme is an index that identifies regions in space where the correction provided by the confined electron gas should be applied. The electron localization function (ELF) is a well-known indicator of strongly localized electrons. We use a model of a confined electron gas based on the harmonic oscillator to show that regions with high ELF directly coincide with regions where common exchange energy functionals have large errors. This suggests that the harmonic oscillator model together with an index based on the ELF provides the crucial ingredients for future improved semi-local functionals. For a practical illustration of how the proposed scheme is intended to work for a physical system we discuss monoclinic cupric oxide, CuO. A thorough discussion of this system leads us to promote the cell geometry of CuO as a useful benchmark for future semi-local functionals. Very high ELF values are found in a shell around the O ions, and take its maximum value along the CuO directions. An estimate of the exchange functional error from the effect of electron confinement in these regions suggests a magnitude and sign that could account for the error in cell geometry.

Hao, Feng, E-mail: hfeng413@gmail.com; Mattsson, Ann E., E-mail: aematts@sandia.gov [Multi-Scale Science MS 1322, Sandia National Laboratories, Albuquerque, New Mexico 87185-1322 (United States); Armiento, Rickard [Department of Physics, Chemistry and Biology (IFM), Linkping University, SE-58183 Linkping (Sweden)] [Department of Physics, Chemistry and Biology (IFM), Linkping University, SE-58183 Linkping (Sweden)

2014-05-14T23:59:59.000Z

245

Excitation energies of molecules within time-independent density functional theory  

SciTech Connect (OSTI)

Recently proposed exchange energy functional for excited-states is tested for obtaining excitation energies of diatomic molecules. The functional is the ground-state counterpart of the local-density approximation, the modified local spin density (MLSD). The MLSD functional is tested for the N{sub 2} and CO diatomic molecules. The excitation energy obtained with the MLSD functional for the N{sub 2} molecule is in close vicinity to that obtained from the exact exchange orbital functional, Krieger, Li and Iafrate (KLI). For the CO molecule, the departure in excitation energy is observed and is due to the overcorrection of self-interaction.

Hemanadhan, M., E-mail: hemanadh@iitk.ac.in; Harbola, Manoj K., E-mail: hemanadh@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016 (India)

2014-04-24T23:59:59.000Z

246

Uranium (VI)Bis(imido) chalcogenate complexes:synthesis and density functional theory analysis  

SciTech Connect (OSTI)

Bis(imido) uranium(VI) trans- and cis-dichalcogenate complexes with the general formula U(NtBu)2(EAr)2(OPPh3)2 (EAr = O-2-tBuC6H4, SPh, SePh, TePh) and U(NtBu)2(EAr)2(R2bpy) (EAr = SPh, SePh, TePh) (R2bpy = 4,4'-disubstituted-2,2'-bipyridyl, R = Me, tBu) have been prepared. This family of complexes includes the first reported monodentate selenolate and tellurolate complexes of uranium(VI). Density functional theory calculations show that covalent interactions in the U-E bond increase in the trans-dichalcogenate series U(NtBu)2(EAr)2(OPPh3)2 as the size of the chalcogenate donor increases and that both 5f and 6d orbital participation is important in the M-E bonds of U-S, U-Se, and U-Te complexes.

Spencer, Liam P [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Yang, Ping [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

247

Spontaneous fission modes and lifetimes of super-heavy elements in the nuclear density functional theory  

E-Print Network [OSTI]

Lifetimes of super-heavy (SH) nuclei are primarily governed by alpha decay and spontaneous fission (SF). Here we study the competing decay modes of even-even SH isotopes with 108 density functional theory framework capable of describing the competition between nuclear attraction and electrostatic repulsion. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov approach. Along the path to fission, our calculations allow for the simultaneous breaking of axial and space inversion symmetries; this may result in lowering SF lifetimes by more than seven orders of magnitude in some cases. We predict two competing SF modes: reflection-symmetric and reflection-asymmetric.The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by $^{280}$Hs, $^{284}$Fl, and $^{284}_{118}$Uuo that separates the regions of SH nuclei synthesized in "cold fusion" and "hot fusion" reactions. The region of long-lived SH nuclei is expected to be centered on $^{294}$Ds with a total half-life of ?1.5 days.

A. Staszczak; A. Baran; W. Nazarewicz

2012-08-06T23:59:59.000Z

248

Efficient iterative method for solving the Dirac-Kohn-Sham density functional theory  

SciTech Connect (OSTI)

We present for the first time an efficient iterative method to directly solve the four-component Dirac-Kohn-Sham (DKS) density functional theory. Due to the existence of the negative energy continuum in the DKS operator, the existing iterative techniques for solving the Kohn-Sham systems cannot be efficiently applied to solve the DKS systems. The key component of our method is a novel filtering step (F) which acts as a preconditioner in the framework of the locally optimal block preconditioned conjugate gradient (LOBPCG) method. The resulting method, dubbed the LOBPCG-F method, is able to compute the desired eigenvalues and eigenvectors in the positive energy band without computing any state in the negative energy band. The LOBPCG-F method introduces mild extra cost compared to the standard LOBPCG method and can be easily implemented. We demonstrate our method in the pseudopotential framework with a planewave basis set which naturally satisfies the kinetic balance prescription. Numerical results for Pt$_{2}$, Au$_{2}$, TlF, and Bi$_{2}$Se$_{3}$ indicate that the LOBPCG-F method is a robust and efficient method for investigating the relativistic effect in systems containing heavy elements.

Lin, Lin; Shao, Sihong; E, Weinan

2012-11-06T23:59:59.000Z

249

Density functional theory and Kohn-Sham scheme for self-bound systems  

E-Print Network [OSTI]

We demonstrate how the separation of the total energy of a self-bound system into a functional of the internal one-body Fermionic density and a function of an arbitrary wave vector describing the center-of-mass kinetic energy can be used to set-up an "internal" Kohn-Sham scheme.

J. Messud; M. Bender; E. Suraud

2009-11-10T23:59:59.000Z

250

Linear Relationship Between Weighted-Average Madelung and Density Functional Theory Energies for MgO Nanotubes  

E-Print Network [OSTI]

Energies for MgO Nanotubes Journal: The Journal of Physical Chemistry Manuscript ID: jp-2012-08041d.R1 Constants and Density Functional Theory Energies for MgO Nanotubes Mark D. Baker,*1 A. David Baker2 , Jane-average Madelung constants of MgO nanotubes correlate in an essentially perfectly linear way with cohesive energies

Hanusa, Christopher

251

Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory  

SciTech Connect (OSTI)

Background: The reactions with the neutron-rich 48Ca beam and actinide targets resulted in the detection of new superheavy (SH) nuclides with Z=104 118. The unambiguous identification of the new isotopes, however, still poses a problem because their -decay chains terminate by spontaneous fission (SF) before reaching the known region of the nuclear chart. The understanding of the competition between -decay and SF channels in SH nuclei is, therefore, of crucial importance for our ability to map the SH region and to assess its extent.

Purpose: We perform self-consistent calculations of the competing decay modes of even-even SH isotopes with 108 Z 126 and 148 N 188.

Methods: We use the state-of-the-art computational framework based on self-consistent symmetry-unrestricted nuclear density functional theory capable of describing the competition between nuclear attraction and electrostatic repulsion. We apply the SkM* Skyrme energy density functional. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (HFB) approach. This paper constitutes a systematic self-consistent study of spontaneous fission in the SH region, carried out at a full HFB level, that simultaneously takes into account both triaxiality and reflection asymmetry.

Results: Breaking axial symmetry and parity turns out to be crucial for a realistic estimate of collective action; it results in lowering SF lifetimes by more than 7 orders of magnitude in some cases. We predict two competing SF modes: reflection symmetric modes and reflection asymmetric modes.

Conclusions: The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by 280Hs, 284Fl, and 118284Uuo that separates the regions of SH nuclei synthesized in cold-fusion and hot-fusion reactions. The region of long-lived SH nuclei is expected to be centered on 294Ds with a total half-life of 1.5 days. Our survey provides a solid benchmark for the future improvements of self-consistent SF calculations in the region of SH nuclei.

Staszczak, A, [UTK/ORNL/Inst. Physics, Maria Curie-Sklodowska University, Poland; Baran, A. [UTK/ORNL/Inst. Physics, Maria Curie-Sklodowska University, Poland; Nazarewicz, Witold [UTK/ORNL/University of Warsaw

2013-01-01T23:59:59.000Z

252

Nonaxial-octupole Y_{32} correlations in N = 150 isotones from multidimensional constrained covariant density functional theories  

E-Print Network [OSTI]

The non-axial reflection-asymmetric $\\beta_{32}$ shape in some transfermium nuclei with N=150, namely $^{246}$Cm, $^{248}$Cf, $^{250}$Fm, and $^{252}$No are investigated with multidimensional constrained covariant density functional theories. By using the density-dependent point coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel, it is found that, for the ground states of $^{248}$Cf and $^{250}$Fm, the non-axial octupole deformation parameter $\\beta_{32} > 0.03$ and the energy gain due to the $\\beta_{32}$ distortion is larger than 300 keV. In $^{246}$Cm and $^{252}$No, shallow $\\beta_{32}$ minima are found. The occurrence of the non-axial octupole $\\beta_{32}$ correlations is mainly from a pair of neutron orbitals $[734]9/2$ ($\

Jie Zhao; Bing-Nan Lu; En-Guang Zhao; Shan-Gui Zhou

2012-09-28T23:59:59.000Z

253

Vacancy diffusion in colloidal crystals as determined by dynamical density-functional theory and the phase-field-crystal model  

E-Print Network [OSTI]

A two-dimensional crystal of repulsive dipolar particles is studied in the vicinity of its melting transition by using Brownian dynamics computer simulation, dynamical density functional theory and phase-field crystal modelling. A vacancy is created by taking out a particle from an equilibrated crystal and the relaxation dynamics of the vacancy is followed by monitoring the time-dependent one-particle density. We find that the vacancy is quickly filled up by diffusive hopping of neighbouring particles towards the vacancy center. We examine the temperature dependence of the diffusion constant and find that it decreases with decreasing temperature in the simulations. This trend is reproduced by the dynamical density functional theory. Conversely, the phase field crystal calculations predict the opposite trend. Therefore, the phase-field model needs a temperature-dependent expression for the mobility to predict trends correctly.

Sven van Teeffelen; Cristian Vasile Achim; Hartmut Lwen

2013-02-05T23:59:59.000Z

254

Higher-order adaptive finite-element methods for KohnSham density functional theory  

SciTech Connect (OSTI)

We present an efficient computational approach to perform real-space electronic structure calculations using an adaptive higher-order finite-element discretization of KohnSham density-functional theory (DFT). To this end, we develop an a priori mesh-adaption technique to construct a close to optimal finite-element discretization of the problem. We further propose an efficient solution strategy for solving the discrete eigenvalue problem by using spectral finite-elements in conjunction with GaussLobatto quadrature, and a Chebyshev acceleration technique for computing the occupied eigenspace. The proposed approach has been observed to provide a staggering 100200-fold computational advantage over the solution of a generalized eigenvalue problem. Using the proposed solution procedure, we investigate the computational efficiency afforded by higher-order finite-element discretizations of the KohnSham DFT problem. Our studies suggest that staggering computational savingsof the order of 1000-foldrelative to linear finite-elements can be realized, for both all-electron and local pseudopotential calculations, by using higher-order finite-element discretizations. On all the benchmark systems studied, we observe diminishing returns in computational savings beyond the sixth-order for accuracies commensurate with chemical accuracy, suggesting that the hexic spectral-element may be an optimal choice for the finite-element discretization of the KohnSham DFT problem. A comparative study of the computational efficiency of the proposed higher-order finite-element discretizations suggests that the performance of finite-element basis is competing with the plane-wave discretization for non-periodic local pseudopotential calculations, and compares to the Gaussian basis for all-electron calculations to within an order of magnitude. Further, we demonstrate the capability of the proposed approach to compute the electronic structure of a metallic system containing 1688 atoms using modest computational resources, and good scalability of the present implementation up to 192 processors.

Motamarri, P. [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Nowak, M.R. [Department of Electrical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Electrical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Leiter, K.; Knap, J. [U.S. Army Research Labs, Aberdeen Proving Ground, Aberdeen, MD 21001 (United States)] [U.S. Army Research Labs, Aberdeen Proving Ground, Aberdeen, MD 21001 (United States); Gavini, V., E-mail: vikramg@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

2013-11-15T23:59:59.000Z

255

Magnetism in undoped ZnS studied from density functional theory  

SciTech Connect (OSTI)

The magnetic property induced by the native defects in ZnS bulk, thin film, and quantum dots are investigated comprehensively based on density functional theory within the generalized gradient approximation + Hubbard U (GGA?+?U) approach. We find the origin of magnetism is closely related to the introduction of hole into ZnS systems. The relative localization of S-3p orbitals is another key to resulting in unpaired p-electron, due to Hund's rule. For almost all the ZnS systems under study, the magnetic moment arises from the S-dangling bonds generated by Zn vacancies. The charge-neutral Zn vacancy, Zn vacancy in 1? charge sate, and S vacancy in the 1+ charge sate produce a local magnetic moment of 2.0, 1.0, and 1.0??{sub B}, respectively. The Zn vacancy in the neutral and 1? charge sates are the important cause for the ferromagnetism in ZnS bulk, with a Curie temperature (T{sub C}) above room temperature. For ZnS thin film with clean (111) surfaces, the spins on each surface are ferromagnetically coupled but antiferromagnetically coupled between two surfaces, which is attributable to the internal electric field between the two polar (111) surfaces of the thin film. Only surface Zn vacancies can yield local magnetic moment for ZnS thin film and quantum dot, which is ascribed to the surface effect. Interactions between magnetic moments on S-3p states induced by hole-doping are responsible for the ferromagnetism observed experimentally in various ZnS samples.

Xiao, Wen-Zhi, E-mail: xiaowenzhi@hnu.edu.cn, E-mail: llwang@hun.edu.cn; Rong, Qing-Yan; Xiao, Gang [Department of Physics and Mathematics, Hunan Institute of Engineering, Xiangtan 411104 (China); Wang, Ling-ling, E-mail: xiaowenzhi@hnu.edu.cn, E-mail: llwang@hun.edu.cn [School of Physics and Microelectronics and Key Lab for Micro-Nano Physics and Technology of Hunan Province, Hunan University, Changsha 410082 (China); Meng, Bo [College of Physics and Electronic Engineering, Caili University, Kaili 556011 (China)

2014-06-07T23:59:59.000Z

256

Relativistic density-functional theory with the optimized effective potential and self-interaction correction: Application to atomic structure calculations ,,Z 2106...  

E-Print Network [OSTI]

Relativistic density-functional theory with the optimized effective potential and self, Lawrence, Kansas 66045 Received 30 July 1997 We present a self-interaction-free relativistic density-functional-2947 98 06201-5 PACS number s : 31.15.Ew, 32.10.Hq, 71.15.Rf I. INTRODUCTION In recent years, the density-functional

Chu, Shih-I

257

Introducing constricted variational density functional theory in its relaxed self-consistent formulation (RSCF-CV-DFT) as an alternative to adiabatic time dependent density functional theory for studies of charge transfer transitions  

SciTech Connect (OSTI)

We have applied the relaxed and self-consistent extension of constricted variational density functional theory (RSCF-CV-DFT) for the calculation of the lowest charge transfer transitions in the molecular complex X-TCNE between X = benzene and TCNE = tetracyanoethylene. Use was made of functionals with a fixed fraction (?) of Hartree-Fock exchange ranging from ? = 0 to ? = 0.5 as well as functionals with a long range correction (LC) that introduces Hartree-Fock exchange for longer inter-electronic distances. A detailed comparison and analysis is given for each functional between the performance of RSCF-CV-DFT and adiabatic time-dependent density functional theory (TDDFT) within the Tamm-Dancoff approximation. It is shown that in this particular case, all functionals afford the same reasonable agreement with experiment for RSCF-CV-DFT whereas only the LC-functionals afford a fair agreement with experiment using TDDFT. We have in addition calculated the CT transition energy for X-TCNE with X = toluene, o-xylene, and naphthalene employing the same functionals as for X = benzene. It is shown that the calculated charge transfer excitation energies are in as good agreement with experiment as those obtained from highly optimized LC-functionals using adiabatic TDDFT. We finally discuss the relation between the optimization of length separation parameters and orbital relaxation in the RSCF-CV-DFT scheme.

Krykunov, Mykhaylo; Seth, Mike; Ziegler, Tom [Department of Chemistry, University of Calgary, University Drive 2500, Calgary, Alberta T2N 1N4 (Canada)] [Department of Chemistry, University of Calgary, University Drive 2500, Calgary, Alberta T2N 1N4 (Canada)

2014-05-14T23:59:59.000Z

258

A Hybrid Density Functional Theory for Solvation and Solvent-Mediated Interactions  

E-Print Network [OSTI]

correlation functions of SPC/E water in Fourier space. (a)of cations and anions in SPC/E water obtained from differentis 300K and mass density of SPC/E water is 0.996 g/cm 3 .

Jin, Zhehui

2012-01-01T23:59:59.000Z

259

Adsorption of supramolecular building blocks on graphite: A force field and density functional theory study  

E-Print Network [OSTI]

that both adsorption energies as well as adsorption geometries of or- ganic molecules on graphite determined studies in which the adsorption energies of supramolecular building blocks are measured.12 This hampersAdsorption of supramolecular building blocks on graphite: A force field and density functional

Pfeifer, Holger

260

Relativistic density-functional theory with the optimized effective potential and self-interaction correction: Application to atomic structure calculations (Z=2106)  

E-Print Network [OSTI]

We present a self-interaction-free relativistic density-functional theory (DFT). The theory is based on the extension of our recent nonrelativistic DFT treatment with optimized effective potential (OEP) and self-interaction ...

Chu, Shih-I; Tong, Xiao-Min

1998-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Covariance analysis of finite temperature density functional theory: symmetric nuclear matter  

E-Print Network [OSTI]

We study symmetric nuclear matter at finite temperature, with particular emphasis on the liquid-gas phase transition. We use a standard covariance analysis to propagate statistical uncertainties from the density functional to the thermodynamic properties. We use four functionals with known covariance matrices to obtain as wide a set of results as possible. Our findings suggest that thermodynamical properties are very well constrained by fitting data at zero temperature. The propagated statistical errors in the liquid-gas phase transition parameters are relatively small.

A. Rios; X. Roca-Maza

2014-08-21T23:59:59.000Z

262

Electronic responses of long chains to electrostatic fields: Hartree-Fock vs. density-functional theory: A model study  

SciTech Connect (OSTI)

The response to an electrostatic field is determined through simple model calculations, within both the restricted Hartree-Fock and density functional theory methods, for long, finite as well as infinite, periodic chains. The permanent dipole moment, ?{sub 0}, the polarizability, ?, and the hyperpolarizabilities ? and ?, calculated using a finite-field approach, are extensively analyzed. Our simple model allows for treatment of large systems and for separation of the properties into atomic and unit-cell contributions. That part of the response properties attributable to the terminations of the finite system change into delocalized current contributions in the corresponding infinite periodic system. Special emphasis is placed on analyzing the reasons behind the dramatic overestimation of the response properties found with density functional theory methods presently in common use.

Vargas, Jorge, E-mail: j.vargas@mx.uni-saarland.de [Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrcken (Germany)] [Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrcken (Germany); Springborg, Michael, E-mail: m.springborg@mx.uni-saarland.de [Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrcken (Germany) [Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrcken (Germany); School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Kirtman, Bernard [Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106 (United States)] [Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106 (United States)

2014-02-07T23:59:59.000Z

263

Density functional theory study of oxygen and water adsorption on SrTiO3(001)  

E-Print Network [OSTI]

effortlessly leading to the formation of a pair of hydroxyl groups. For the titanium dioxide termina- tionDensity functional theory study of oxygen and water adsorption on SrTiO3(001) D I S S E R TAT I O N and they are computationally feasible. For the oxygen and water adsorption the binding energy is controlled by long-range sur

264

Functional approach for pairing in finite systems: How to define restoration of broken symmetries in Energy Density Functional theory ?  

E-Print Network [OSTI]

The Multi-Reference Energy Density Functional (MR-EDF) approach (also called configuration mixing or Generator Coordinate Method), that is commonly used to treat pairing in finite nuclei and project onto particle number, is re-analyzed. It is shown that, under certain conditions, the MR-EDF energy can be interpreted as a functional of the one-body density matrix of the projected state with good particle number. Based on this observation, we propose a new approach, called Symmetry-Conserving EDF (SC-EDF), where the breaking and restoration of symmetry are accounted for simultaneously. We show, that such an approach is free from pathologies recently observed in MR-EDF and can be used with a large flexibility on the density dependence of the functional.

Guillaume Hupin; Denis Lacroix; Michael Bender

2011-05-30T23:59:59.000Z

265

Comparison of Small Polaron Migration and Phase Separation in Olivine LiMnPO? and LiFePO? using Hybrid Density Functional Theory  

E-Print Network [OSTI]

Using hybrid density functional theory based on the Heyd-Scuseria-Ernzerhof (HSE06) functional, we compared polaron migration and phase separation in olivine LiMnPO? to LiFePO?. The barriers for free hole and electron ...

Ong, Shyue Ping

266

Generalization of internal Density Functional Theory and Kohn-Sham scheme to multicomponent systems, and link with traditional DFT  

E-Print Network [OSTI]

We generalize the recently developped "internal" Density Functional Theory (DFT) and Kohn-Sham scheme to multicomponent systems. We obtain a general formalism, applicable for the description of multicomponent self-bound systems (as molecules where the nuclei are treated explicitely, atomic nuclei and mix of 3He and 4He droplets), where the fundamental translational symmetry has been treated correctly. The main difference with traditional DFT is the explicit inclusion of center-of-mass correlations in the functional. A large part of the paper is dedicated to the application to molecules, which permits among other to clarify the approximations that underly traditional DFT.

Jeremie Messud

2011-11-21T23:59:59.000Z

267

Fermi Orbital Derivatives in Self-Interaction Corrected Density Functional Theory: Applications to Closed Shell Atoms  

E-Print Network [OSTI]

A recent modification of the Perdew-Zunger self-interaction-correction (SIC) to the density-functional formalism (Pederson, Ruzsinszky, Perdew) has provided a framework for explicitly restoring unitary invariance to the expression for the total energy. The formalism depends upon construction of Lowdin orthonormalized Fermi-orbitals (Luken et al) which parametrically depend on variational quasi-classical electronic positions. Derivatives of these quasi-classical electronic positions, required for efficient minimization of the self-interaction corrected energy, are derived and tested here on atoms. Total energies and ionization energies in closed-shell atoms, where correlation is less important, using the PW92 LDA functional are in very good to excellent agreement with experiment and non-relativistic Quantum-Monte-Carlo (QMC) results.

Mark R. Pederson

2014-12-13T23:59:59.000Z

268

Density functional theory for the description of spherical non-associating monomers in confined media using the SAFT-VR equation of state and weighted density approximations  

SciTech Connect (OSTI)

As a first step of an ongoing study of thermodynamic properties and adsorption of complex fluids in confined media, we present a new theoretical description for spherical monomers using the Statistical Associating Fluid Theory for potential of Variable Range (SAFT-VR) and a Non-Local Density Functional Theory (NLDFT) with Weighted Density Approximations (WDA). The well-known Modified Fundamental Measure Theory is used to describe the inhomogeneous hard-sphere contribution as a reference for the monomer and two WDA approaches are developed for the dispersive terms from the high-temperature Barker and Henderson perturbation expansion. The first approach extends the dispersive contributions using the scalar and vector weighted densities introduced in the Fundamental Measure Theory (FMT) and the second one uses a coarse-grained (CG) approach with a unique weighted density. To test the accuracy of this new NLDFT/SAFT-VR coupling, the two versions of the theoretical model are compared with Grand Canonical Monte Carlo (GCMC) molecular simulations using the same molecular model. Only the version with the CG approach for the dispersive terms provides results in excellent agreement with GCMC calculations in a wide range of conditions while the FMT extension version gives a good representation solely at low pressures. Hence, the CG version of the theoretical model is used to reproduce methane adsorption isotherms in a Carbon Molecular Sieve and compared with experimental data after a characterization of the material. The whole results show an excellent agreement between modeling and experiments. Thus, through a complete and consistent comparison both with molecular simulations and with experimental data, the NLDFT/SAFT-VR theory has been validated for the description of monomers.

Malheiro, Carine; Mendiboure, Bruno; Plantier, Frdric; Miqueu, Christelle [Universit Pau et Pays Adour, CNRS, TOTAL - UMR 5150 LFC-R Laboratoire des Fluides Complexes et leurs Rservoirs, BP 1155 PAU, F-64013 (France)] [Universit Pau et Pays Adour, CNRS, TOTAL - UMR 5150 LFC-R Laboratoire des Fluides Complexes et leurs Rservoirs, BP 1155 PAU, F-64013 (France); Blas, Felipe J. [Departamento de Fsica Aplicada, and Centro de Fsica Terica y Matemtica FIMAT, Universidad de Huelva, 21071 Huelva (Spain)] [Departamento de Fsica Aplicada, and Centro de Fsica Terica y Matemtica FIMAT, Universidad de Huelva, 21071 Huelva (Spain)

2014-04-07T23:59:59.000Z

269

A density-functional theory investigation of cluster formation in an effective-potential model of dendrimers  

E-Print Network [OSTI]

We consider a system of particles interacting via a purely repulsive, soft-core potential recently introduced to model effective pair interactions between dendrimers, which is expected to lead to the formation of crystals with multiple occupancy of the lattice sites. The phase diagram is investigated by density-functional theory (DFT) without making any a priori assumption on the functional form of the density profile or on the type of crystal lattice. As the average density $\\rho$ is increased, the system displays first a transition from a fluid to a bcc phase, and subsequently to hcp and fcc phases. In the inhomogeneous region, the behavior is that found in previous investigations of this class of cluster-forming potentials. Specifically, the particles arrange into clusters strongly localized at the lattice sites, and the lattice constant depends very weakly on $\\rho$, leading to an occupancy number of the sites which is a nearly linear function of $\\rho$. These results are compared to those predicted by the more widespread approach, in which the DFT minimization is carried out by representing the density profile by a given functional form depending on few variational parameters. We find that for the model potential studied here, the latter approach recovers most of the predictions of the unconstrained minimization.

Davide Pini

2014-07-04T23:59:59.000Z

270

Crucial test for covariant density functional theory with new and accurate mass measurements from Sn to Pa  

E-Print Network [OSTI]

The covariant density functional theory with the point-coupling interaction PC-PK1 is compared with new and accurate experimental masses in the element range from 50 to 91. The experimental data are from a mass measurement performed with the storage ring mass spectrometry at GSI [Chen et al., Nucl. Phys. A 882, 71 (2012)]. Although the microscopic theory contains only 11 parameters, it agrees well with the experimental data. The comparison is characterized by a rms deviation of 0.859 MeV. For even-even nuclei, the theory agrees within about 600 keV. Larger deviations are observed in this comparison for the odd-A and odd-odd nuclei. Improvements and possible reasons for the deviations are discussed in this contribution as well.

P. W. Zhao; L. S. Song; B. Sun; H. Geissel; J. Meng

2012-12-31T23:59:59.000Z

271

Searching for 4$?$ linear-chain structure in excited states of $^{16}$O with a covariant density functional theory  

E-Print Network [OSTI]

A study of 4$\\alpha$ linear-chain structure in high-lying collective excitation states of $^{16}$O with a covariant density functional theory is presented. The low-spin states are obtained by configuration mixing of particle-number and angular-momentum projected quadrupole deformed mean-field states with generator coordinate method. The high-spin states are determined by cranking calculations. These two calculations are based on the same energy density functional PC-PK1. We have found a rotational band at low-spin with the dominated intrinsic configuration considered to be the one that 4$\\alpha$ clusters stay along a common axis. The strongly deformed rod shape also appears in the high-spin region with the angular momentum $13-18\\hbar$; however whether the state is pure $4\\alpha$ linear chain or not is less obvious than that in the low-spin states.

J. M. Yao; N. Itagaki; J. Meng

2014-09-19T23:59:59.000Z

272

Derivation of a three-dimensional phase-field-crystal model for liquid crystals from density functional theory  

E-Print Network [OSTI]

Using a generalized order parameter gradient expansion within density functional theory, we derive a phase-field-crystal model for liquid crystals composed by apolar particles in three spatial dimensions. Both the translational density and the orientational direction and ordering are included as order parameters. Different terms involving gradients in the order parameters in the resulting free energy functional are compared to the macroscopic Ginzburg-Landau approach as well as to the hydrodynamic description for liquid crystals. Our approach provides microscopic expressions for all prefactors in terms of the particle interactions. Our phase-field-crystal model generalizes the conventional phase-field-crystal model of spherical particles to orientational degrees of freedom and can be used as a starting point to explore phase transitions and interfaces for various liquid-crystalline phases.

Raphael Wittkowski; Hartmut Lwen; Helmut R. Brand

2010-07-09T23:59:59.000Z

273

A density functional theory model of mechanically activated silyl ester hydrolysis  

SciTech Connect (OSTI)

To elucidate the mechanism of the mechanically activated dissociation of chemical bonds between carboxymethylated amylose (CMA) and silane functionalized silicon dioxide, we have investigated the dissociation kinetics of the bonds connecting CMA to silicon oxide surfaces with density functional calculations including the effects of force, solvent polarizability, and pH. We have determined the activation energies, the pre-exponential factors, and the reaction rate constants of candidate reactions. The weakest bond was found to be the silyl ester bond between the silicon and the alkoxy oxygen atom. Under acidic conditions, spontaneous proton addition occurs close to the silyl ester such that neutral reactions become insignificant. Upon proton addition at the most favored position, the activation energy for bond hydrolysis becomes 31 kJ?mol{sup ?1}, which agrees very well with experimental observation. Heterolytic bond scission in the protonated molecule has a much higher activation energy. The experimentally observed bi-exponential rupture kinetics can be explained by different side groups attached to the silicon atom of the silyl ester. The fact that different side groups lead to different dissociation kinetics provides an opportunity to deliberately modify and tune the kinetic parameters of mechanically activated bond dissociation of silyl esters.

Pill, Michael F.; Schmidt, Sebastian W. [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany) [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany); Institut fr Physikalische Chemie, Christian-Albrechts-Universitt zu Kiel, Olshausenstrae 40, 24098 Kiel (Germany); Center for Nanoscience (CeNS), Geschwister-Scholl-Platz 1, 80539 Munich (Germany); Beyer, Martin K. [Institut fr Physikalische Chemie, Christian-Albrechts-Universitt zu Kiel, Olshausenstrae 40, 24098 Kiel (Germany) [Institut fr Physikalische Chemie, Christian-Albrechts-Universitt zu Kiel, Olshausenstrae 40, 24098 Kiel (Germany); Institut fr Ionenphysik und Angewandte Physik, Leopold-Franzens-Universitt Innsbruck, Technikerstrae 25, 6020 Innsbruck (Austria); Clausen-Schaumann, Hauke [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany) [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany); Center for Nanoscience (CeNS), Geschwister-Scholl-Platz 1, 80539 Munich (Germany); Kersch, Alfred, E-mail: akersch@hm.edu [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany)] [Department of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstr. 34, 80335 Munich (Germany)

2014-01-28T23:59:59.000Z

274

BiFeO3 Domain Wall Energies and Structures: A Combined Experimental and Density Functional Theory+U Study  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We determined the atomic structures and energies of 109, 180, and 71 domain walls in BiFeO3, combining density functional theory+U calculations and aberration-corrected transmission electron microscopy images. We find a substantial Bi sublattice shift and a rather uniform Fe sublattice across the walls. The calculated wall energies (?) follow the sequence ?109 180 71 for the 109, 180, and 71 walls. We attribute the high 71 wall energy to an opposite tilting rotation of the oxygen octahedra and the low 109 wall energy to the opposite twisting rotation of the oxygen octahedra across the domain walls.

Wang, Yi; Nelson, Chris; Melville, Alexander; Winchester, Benjamin; Shang, Shunli; Liu, Zi-Kui; Schlom, Darrell G.; Pan, Xiaoqing; Chen, Long-Qing

2013-06-01T23:59:59.000Z

275

Description of interfaces of fluid-tethered chains: advances in density functional theories and off-lattice computer simulations  

E-Print Network [OSTI]

Many objects of nanoscopic dimensions involve fluid-tethered chain interfaces. These systems are of interest for basic science and for several applications, in particular for design of nanodevices for specific purposes. We review recent developments of theoretical methods in this area of research and in particular of density functional (DF) approaches, which provide important insights into microscopic properties of such interfaces. The theories permit to describe the dependence of adsorption, wettability, solvation forces and electric interfacial phenomena on thermodynamic states and on characteristics of tethered chains. Computer simulations for the problems in question are overviewed as well. Theoretical results are discussed in relation to simulation results and to some experimental observations.

S. Soko?owski; J. Ilnytskyi; O. Pizio

2014-03-06T23:59:59.000Z

276

Core and Valence Excitations in Resonant X-ray Spectroscopy using Restricted Excitation Window Time-dependent Density Functional Theory  

SciTech Connect (OSTI)

We report simulations of X-ray absorption near edge structure (XANES), resonant inelastic X-ray scattering (RIXS) and 1D stimulated X-ray Raman spectroscopy (SXRS) signals of cysteine at the oxygen, nitrogen and sulfur K and L2,3 edges. The simulated XANES signals from the restricted window time-dependent density functional theory (REW-TDDFT) and the static exchange (STEX) method are compared with experiments, showing that REW-TDDFT is more accurate and computationally less expensive than STEX. Simulated RIXS and 1D SXRS signals from REW-TDDFT give some insights on the correlation of different excitations in the molecule.

Zhang, Yu; Biggs, Jason D.; Healion, Daniel; Govind, Niranjan; Mukamel, Shaul

2012-11-21T23:59:59.000Z

277

Excitations and benchmark ensemble density functional theory for two electrons Aurora Pribram-Jones, Zeng-hui Yang, John R. Trail, Kieron Burke, Richard J. Needs, and Carsten A. Ullrich  

E-Print Network [OSTI]

Excitations and benchmark ensemble density functional theory for two electrons Aurora Pribram and benchmark ensemble density functional theory for two electrons Aurora Pribram-Jones,1 Zeng-hui Yang,2 John R

Burke, Kieron

278

Complex-energy approach to sum rules within nuclear density functional theory  

E-Print Network [OSTI]

The linear response of the nucleus to an external field contains unique information about the effective interaction, correlations, and properties of its excited states. To characterize the response, it is useful to use its energy-weighted moments, or sum rules. By comparing computed sum rules with experimental values, the information content of the response can be utilized in the optimization process of the nuclear Hamiltonian or EDF. But the additional information comes at a price: compared to the ground state, computation of excited states is more demanding. To establish an efficient framework to compute sum rules of the response that is adaptable to the optimization of the nuclear EDF and large-scale surveys of collective strength, we have developed a new technique within the complex-energy FAM based on the QRPA. To compute sum rules, we carry out contour integration of the response function in the complex-energy plane. We benchmark our results against the conventional matrix formulation of the QRPA theory...

Hinohara, Nobuo; Nazarewicz, Witold; Olsen, Erik

2015-01-01T23:59:59.000Z

279

Near and Above Ionization Electronic Excitations with Non-Hermitian Real-Time Time-Dependent Density Functional Theory  

SciTech Connect (OSTI)

We present a real-time time-dependent density functional theory (RT-TDDFT) prescription for capturing near and post-ionization excitations based on non-Hermitian von Neumann density matrix propagation with atom-centered basis sets, tuned range-separated DFT, and a phenomenological imaginary molecular orbital-based absorbing potential to mimic coupling to the continuum. The computed extreme ultraviolet absorption spectra for acetylene (C2H2), water (H2O), and Freon 12 (CF2Cl2) agree well with electron energy loss spectroscopy (EELS) data over the range 0 to 50 eV. The absorbing potential removes spurious high energy finite basis artifacts, yielding correct bound to bound transitions, metastable (autoionizing) resonance states, and consistent overall absorption shapes.

Lopata, Kenneth A.; Govind, Niranjan

2013-11-12T23:59:59.000Z

280

Self-interaction-free time-dependent density-functional theory for molecular processes in strong fields: High-order harmonic generation of H2 in intense laser fields  

E-Print Network [OSTI]

Self-interaction-free time-dependent density-functional theory for molecular processes in strong work of Hohenberg and Kohn 1 and Kohn and Sham 2 , the steady-state density-functional theory DFT has-electron systems, within the density-functional theory, is much less developed. The central theme of the modern

Chu, Shih-I

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections  

E-Print Network [OSTI]

Molecular Density Functional Theory (MDFT) offers an efficient implicit- solvent method to estimate molecule solvation free-energies whereas conserving a fully molecular representation of the solvent. Even within a second order ap- proximation for the free-energy functional, the so-called homogeneous reference uid approximation, we show that the hydration free-energies computed for a dataset of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by two to three orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canoni- cal to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justifcation to empirical partial molar volume corrections that have been proposed recently.

Volodymyr P. Sergiievskyi; Guillaume Jeanmairet; Maximilien Levesque; Daniel Borgis

2014-06-11T23:59:59.000Z

282

A Systematic Study of Chloride Ion Solvation in Water using van der Waals Inclusive Hybrid Density Functional Theory  

E-Print Network [OSTI]

In this work, the solvation and electronic structure of the aqueous chloride ion solution was investigated using Density Functional Theory (DFT) based \\textit{ab initio} molecular dynamics (AIMD). From an analysis of radial distribution functions, coordination numbers, and solvation structures, we found that exact exchange ($E_{\\rm xx}$) and non-local van der Waals (vdW) interactions effectively \\textit{weaken} the interactions between the Cl$^-$ ion and the first solvation shell. With a Cl-O coordination number in excellent agreement with experiment, we found that most configurations generated with vdW-inclusive hybrid DFT exhibit 6-fold coordinated distorted trigonal prism structures, which is indicative of a significantly disordered first solvation shell. By performing a series of band structure calculations on configurations generated from AIMD simulations with varying DFT potentials, we found that the solvated ion orbital energy levels (unlike the band structure of liquid water) strongly depend on the un...

Bankura, Arindam; DiStasio, Robert A; Swartz, Charles W; Klein, Michael L; Wu, Xifan

2015-01-01T23:59:59.000Z

283

Study of the interaction of solutes with ?5 (013) tilt grain boundaries in iron using density-functional theory  

SciTech Connect (OSTI)

Substitutional alloying elements significantly affect the recrystallization and austenite-ferrite phase transformation rates in steels. The atomistic mechanisms of their interaction with the interfaces are still largely unexplored. Using density functional theory, we determine the segregation energies between commonly used alloying elements and the ?5 (013) tilt grain boundary in bcc iron. We find a strong solute-grain boundary interaction for Nb, Mo, and Ti that is consistent with experimental observations of the effects of these alloying elements on delaying recrystallization and the austenite-to-ferrite transformation in low-carbon steels. In addition, we compute the solute-solute interactions as a function of solute pair distance in the grain boundary, which suggest co-segregation for these large solutes at intermediate distances in striking contrast to the bulk.

Jin, Hao; Militzer, Matthias [Centre for Metallurgical Process Engineering, The University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada); Elfimov, Ilya [Quantum Matter Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada)

2014-03-07T23:59:59.000Z

284

Van der Waals density-functional theory study for bulk solids with BCC, FCC, and diamond structures  

E-Print Network [OSTI]

Proper inclusion of van der Waals (vdW) interactions in theoretical simulations based on standard density functional theory (DFT) is crucial to describe the physics and chemistry of systems such as organic and layered materials. Many encouraging approaches have been proposed to combine vdW interactions with standard approximate DFT calculations. Despite many vdW studies, there is no consensus on the reliability of vdW methods. To help further development of vdW methods, we have assessed various vdW functionals through the calculation of structural prop- erties at equilibrium, such as lattice constants, bulk moduli, and cohesive energies, for bulk solids, including alkali, alkali-earth, and transition metals, with BCC, FCC, and diamond structures as the ground state structure. These results provide important information for the vdW-related materials research, which is essential for designing and optimizing materials systems for desired physical and chemical properties.

Park, Jinwoo; Hong, Suklyun

2015-01-01T23:59:59.000Z

285

Structural and electronic properties of poly(vinyl alcohol) using density functional theory  

SciTech Connect (OSTI)

The first principles calculations have been carried out to investigate the structural, electronic band structure density of states along with the projected density of states for poly(vinyl alcohol). Our structural calculation suggests that the poly(vinyl alcohol) exhibits monoclinic structure. The calculated structural lattice parameters are in excellent agreement with available experimental values. The band structure calculations reveal that the direct and indirect band gaps are 5.55 eV and 5.363 eV respectively in accordance with experimental values.

Dabhi, Shweta, E-mail: shwetadabhi1190@gmail.com; Jha, Prafulla K., E-mail: shwetadabhi1190@gmail.com [Department of Physics, Maharaja Krishnakumasinhji Bhavnagar University, Bhavnagar-364001 (India)

2014-04-24T23:59:59.000Z

286

Density Functional Theory Simulations Predict New Materials for Magnesium-Ion Batteries (Fact Sheet), NREL Highlights, Science  

SciTech Connect (OSTI)

Multivalence is identified in the light element, B, through structure morphology. Boron sheets exhibit highly versatile valence, and the layered boron materials may hold the promise of a high-energy-density magnesium-ion battery. Practically, boron is superior to previously known multivalence materials, especially transition metal compounds, which are heavy, expensive, and often not benign. Based on density functional theory simulations, researchers at the National Renewable Energy Laboratory (NREL) have predicted a series of stable magnesium borides, MgB{sub x}, with a broad range of stoichiometries, 2 < x < 16, by removing magnesium atoms from MgB{sub 2}. The layered boron structures are preserved through an in-plane topological transformation between the hexagonal lattice domains and the triangular domains. The process can be reversibly switched as the charge transfer changes with Mg insertion/extraction. The mechanism of such a charge-driven transformation originates from the versatile valence state of boron in its planar form. The discovery of these new physical phenomena suggests the design of a high-capacity magnesium-boron battery with theoretical energy density 876 mAh/g and 1550 Wh/L.

Not Available

2011-10-01T23:59:59.000Z

287

Density Functional Theory for Protein Transfer Free Energy Eric A. Mills and Steven S. Plotkin*  

E-Print Network [OSTI]

-solvation" repulsive force at larger distances. 1. INTRODUCTION Proteins fold and function in the crowded environment different that the conditions for protein folding are generally mutually exclusive between the two milieu environment on protein folding, stability, and function. Accurately accounting for the effects of the cell

Plotkin, Steven S.

288

Density Functional Theory and Reaction Kinetics Studies of the WaterGas Shift Reaction on PtRe Catalysts  

SciTech Connect (OSTI)

Periodic, self-consistent density functional theory calculations (DFT-GGA-PW91) on Pt(111) and Pt3Re(111) surfaces, reaction kinetics measurements, and microkinetic modeling are employed to study the mechanism of the watergas shift (WGS) reaction over Pt and PtRe catalysts. The values of the reaction rates and reaction orders predicted by the model are in agreement with the ones experimentally determined; the calculated apparent activation energies are matched to within 6% of the experimental values. The primary reaction pathway is predicted to take place through adsorbed carboxyl (COOH) species, whereas formate (HCOO) is predicted to be a spectator species. We conclude that the clean Pt(111) is a good representation of the active site for the WGS reaction on Pt catalysts, whereas the active sites on the PtRe alloy catalyst likely contain partially oxidized metal ensembles.

Carrasquillo-Flores, Ronald; Gallo, Jean Marcel R.; Hahn, Konstanze; Dumesic, James A.; Mavrikakis, Manos

2013-12-01T23:59:59.000Z

289

Permeation of low-Z atoms through carbon sheets: Density functional theory study on energy barriers and deformation effects  

SciTech Connect (OSTI)

Energetic and geometric aspects of the permeation of the atoms hydrogen to neon neutral atoms through graphene sheets are investigated by investigating the associated energy barriers and sheet deformations. Density functional theory calculations on cluster models, where graphene is modeled by planar polycyclic aromatic hydrocarbons (PAHs), provide the energies and geometries. Particularities of our systems, such as convergence of both energy barriers and deformation curves with increasing size of the PAHs, are discussed. Three different interaction regimes, adiabatic, planar and vertical, are investigated by enforcing different geometrical constraints. The adiabatic energy barriers range from 5 eV for hydrogen to 20 eV for neon. We find that the permeation of oxygen and carbon into graphene is facilitated by temporary chemical bonding while for other, in principle reactive atoms, it is not. We discuss implications of our results for modeling chemical sputtering of graphite.

Huber, Stefan E., E-mail: s.huber@uibk.ac.at, E-mail: Michael.probst@uibk.ac.at; Mauracher, Andreas; Probst, Michael, E-mail: s.huber@uibk.ac.at, E-mail: Michael.probst@uibk.ac.at [Institute of Ion Physics and Applied Physics, University of Innsbruck, Technikerstrae 25, 6020 Innsbruck (Austria)] [Institute of Ion Physics and Applied Physics, University of Innsbruck, Technikerstrae 25, 6020 Innsbruck (Austria)

2013-12-15T23:59:59.000Z

290

UV-vis spectra of singlet state cationic polycyclic aromatic hydrocarbons: Time-dependent density functional theory study  

SciTech Connect (OSTI)

A theoretical study of singlet state cations of polycyclic aromatic hydrocarbons is performed. Appropriate symmetry suitable for further calculations is chosen for each of the systems studied. The excitation states of such species are obtained by the time dependent density functional theory (TD-DFT) method. The computations are performed using both Pople and electronic response properties basis sets. The results obtained with the use of different basis sets are compared. The electronic transitions are described and the relationships for the lowest-lying transitions states of different species are found. The properties of in-plane and out-of-plane transitions are also delineated. The TD-DFT results are compared with the experimental data available.

Dominikowska, Justyna, E-mail: justyna@uni.lodz.pl; Domagala, Malgorzata; Palusiak, Marcin [Department of Theoretical and Structural Chemistry, University of ?d?, Pomorska 163/165, 90-236 ?d? (Poland)] [Department of Theoretical and Structural Chemistry, University of ?d?, Pomorska 163/165, 90-236 ?d? (Poland)

2014-01-28T23:59:59.000Z

291

Density Functional Theory for Fractional Particle Number: Derivative Discontinuity of the Energy at the Maximum Number of Bound Electrons  

E-Print Network [OSTI]

The derivative discontinuity in the exact exchange-correlation potential of ensemble Density Functional Theory (DFT) is investigated at the specific integer number that corresponds to the maximum number of bound electrons, $J_{max}$. A recently developed complex-scaled analog of DFT is extended to fractional particle numbers and used to study ensembles of both bound and metastable states. It is found that the exact exchange-correlation potential experiences discontinuous jumps at integer particle numbers including $J_{max}$. For integers below $J_{max}$ the jump is purely real because of the real shift in the chemical potential. At $J_{max}$, the jump has a non-zero imaginary component reflecting the finite lifetime of the $(J_{max}+1)$ state.

Daniel L. Whitenack; Yu Zhang; Adam Wasserman

2011-11-08T23:59:59.000Z

292

Triplet state photochemistry and the three-state crossing of acetophenone within time-dependent density-functional theory  

SciTech Connect (OSTI)

Even though time-dependent density-functional theory (TDDFT) works generally well for describing excited states energies and properties in the Franck-Condon region, it can dramatically fail in predicting photochemistry, notably when electronic state crossings occur. Here, we assess the ability of TDDFT to describe the photochemistry of an important class of triplet sensitizers, namely, aromatic ketones. We take acetophenone as a test molecule, for which accurate ab initio results exist in the literature. Triplet acetophenone is generated thanks to an exotic three-state crossing involving one singlet and two triplets states (i.e., a simultaneous intersystem crossing and triplet conical intersection), thus being a stringent test for approximate TDDFT. We show that most exchange-correlation functionals can only give a semi-qualitative picture of the overall photochemistry, in which the three-state crossing is rather represented as a triplet conical intersection separated from the intersystem crossing. The best result overall is given by the double hybrid functional mPW2PLYP, which is even able to reproduce quantitatively the three-state crossing region. We rationalize this results by noting that double hybrid functionals include a larger portion of double excitation character to the excited states.

Huix-Rotllant, Miquel, E-mail: miquel.huix@gmail.com; Ferr, Nicolas, E-mail: nicolas.ferre@univ-amu.fr [Institut de Chimie Radicalaire (UMR-7273), Aix-Marseille Universit, CNRS, 13397 Marseille Cedex 20 (France)] [Institut de Chimie Radicalaire (UMR-7273), Aix-Marseille Universit, CNRS, 13397 Marseille Cedex 20 (France)

2014-04-07T23:59:59.000Z

293

A Systematic Study of Chloride Ion Solvation in Water using van der Waals Inclusive Hybrid Density Functional Theory  

E-Print Network [OSTI]

In this work, the solvation and electronic structure of the aqueous chloride ion solution was investigated using Density Functional Theory (DFT) based \\textit{ab initio} molecular dynamics (AIMD). From an analysis of radial distribution functions, coordination numbers, and solvation structures, we found that exact exchange ($E_{\\rm xx}$) and non-local van der Waals (vdW) interactions effectively \\textit{weaken} the interactions between the Cl$^-$ ion and the first solvation shell. With a Cl-O coordination number in excellent agreement with experiment, we found that most configurations generated with vdW-inclusive hybrid DFT exhibit 6-fold coordinated distorted trigonal prism structures, which is indicative of a significantly disordered first solvation shell. By performing a series of band structure calculations on configurations generated from AIMD simulations with varying DFT potentials, we found that the solvated ion orbital energy levels (unlike the band structure of liquid water) strongly depend on the underlying molecular structures. In addition, these orbital energy levels were also significantly affected by the DFT functional employed for the electronic structure; as the fraction of $E_{\\rm xx}$ was increased, the gap between the highest occupied molecular orbital of Cl$^-$ and the valence band maximum of liquid water steadily increased towards the experimental value.

Arindam Bankura; Biswajit Santra; Robert A. DiStasio Jr.; Charles W. Swartz; Michael L. Klein; Xifan Wu

2015-03-25T23:59:59.000Z

294

Water-gas Shift Reaction on oxide/Cu(111): Rational Catalyst Screening from Density Functional Theory  

SciTech Connect (OSTI)

Developing improved catalysts based on a fundamental understanding of reaction mechanism has become one of the grand challenges in catalysis. A theoretical understanding and screening the metal-oxide composite catalysts for the water-gas shift (WGS) reaction is presented here. Density functional theory was employed to identify the key step for the WGS reaction on the Au, Cu-oxide catalysts, where the calculated reaction energy for water dissociation correlates well with the experimental measured WGS activity. Accordingly, the calculated reaction energy for water dissociation was used as the scaling descriptor to screen the inverse model catalysts, oxide/Cu(111), for the better WGS activity. Our calculations predict that the WGS activity increases in a sequence: Cu(111), ZnO/Cu(111) < TiO{sub 2}/Cu(111), ZrO{sub 2}/Cu(111) < MoO{sub 3}/Cu(111). Our results imply that the high performances of Au, Cu-oxide nanocatalysts in the WGS reaction rely heavily on the direct participation of both oxide and metal sites. The degree that the oxide is reduced by Cu plays an important role in determining the WGS activity of oxide/Cu catalysts. The reducible oxide can be transformed from the fully oxidized form to the reduced form due to the interaction with Cu and, therefore, the transfer of electron density from Cu, which helps in releasing the bottleneck water dissociation and, therefore, facilitating the WGS reaction on copper.

Liu, P.

2010-11-28T23:59:59.000Z

295

Quantifying the importance of orbital over spin correlations in delta-Pu within density-functional theory  

SciTech Connect (OSTI)

Spin and orbital and electron correlations are known to be important when treating the high-temperature {delta} phase of plutonium within the framework of density-functional theory (DFT). One of the more successful attempts to model {delta}-Pu within this approach has included condensed-matter generalizations of Hund's three rules for atoms, i.e., spin polarization, orbital polarization, and spin-orbit coupling. Here they perform a quantitative analysis of these interactions relative rank for the bonding and electronic structure in {delta}-Pu within the DFT model. The result is somewhat surprising in that spin-orbit coupling and orbital polarization are far more important than spin polarization for a realistic description of {delta}-Pu. They show that these orbital correlations on their own, without any formation of magnetic spin moments, can account for the low atomic density of the {delta} phase with a reasonable equation-of-state. In addition, this unambiguously non-magnetic (NM) treatment produces a one-electron spectra with resonances close to the Fermi level consistent with experimental valence band photoemission spectra.

Soderlind, P; Wolfer, W

2007-07-27T23:59:59.000Z

296

The Structure of Hydrated Electron. Part 1. Magnetic Resonance of Internally Trapping Water Anions: A Density Functional Theory Study  

E-Print Network [OSTI]

Density functional theory (DFT) is used to rationalize magnetic parameters of hydrated electron trapped in alkaline glasses as observed using Electron Paramagnetic Resonance (EPR) and Electron Spin Echo Envelope Modulation (ESEEM) spectroscopies. To this end, model water cluster anions (n=4-8 and n=20,24) that localize the electron internally are examined. It is shown that EPR parameters of such water anions (such as hyperfine coupling tensors of H/D nuclei in the water molecules) are defined mainly by the cavity size and the coordination number of the electron; the water molecules in the second solvation shell play a relatively minor role. An idealized model of hydrated electron (that is usually attributed to L. Kevan) in which six hydroxyl groups arranged in an octahedral pattern point towards the common center is shown to provide the closest match to the experimental parameters, such as isotropic and anisotropic hyperfine coupling constants for the protons (estimated from ESEEM), the second moment of the EPR spectra, and the radius of gyration. The salient feature of these DFT models is the significant transfer (10-20%) of spin density into the frontal O 2p orbitals of water molecules. Spin bond polarization involving these oxygen orbitals accounts for small, negative hyperfine coupling constants for protons in hydroxyl groups that form the electron-trapping cavity. In Part 2, these results are generalized for more realistic geometries of core anions obtained using a dynamic one-electron mixed qunatum/classical molecular dynamics model.

I. A. Shkrob

2006-07-25T23:59:59.000Z

297

Thermal decomposition of 1,3,3-trinitroazetidine (TNAZ): A density functional theory and ab initio study  

SciTech Connect (OSTI)

Density functional theory and ab initio methods are employed to investigate decomposition pathways of 1,3,3-trinitroazetidine initiated by unimolecular loss of NO{sub 2} or HONO. Geometry optimizations are performed using M06/cc-pVTZ and coupled-cluster (CC) theory with single, double, and perturbative triple excitations, CCSD(T), is used to calculate accurate single-point energies for those geometries. The CCSD(T)/cc-pVTZ energies for NO{sub 2} elimination by NN and CN bond fission are, including zero-point energy (ZPE) corrections, 43.21 kcal/mol and 50.46 kcal/mol, respectively. The decomposition initiated by trans-HONO elimination can occur by a concerted H-atom and nitramine NO{sub 2} group elimination or by a concerted H-atom and nitroalkyl NO{sub 2} group elimination via barriers (at the CCSD(T)/cc-pVTZ level with ZPE corrections) of 47.00 kcal/mol and 48.27 kcal/mol, respectively. Thus, at the CCSD(T)/cc-pVTZ level, the ordering of these four decomposition steps from energetically most favored to least favored is: NO{sub 2} elimination by NN bond fission, HONO elimination involving the nitramine NO{sub 2} group, HONO elimination involving a nitroalkyl NO{sub 2} group, and finally NO{sub 2} elimination by CN bond fission.

Veals, Jeffrey D.; Thompson, Donald L. [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)] [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

2014-04-21T23:59:59.000Z

298

New density functional theory approaches for enabling prediction of chemical and physical properties of plutonium and other actinides.  

SciTech Connect (OSTI)

Density Functional Theory (DFT) based Equation of State (EOS) construction is a prominent part of Sandia's capabilities to support engineering sciences. This capability is based on amending experimental data with information gained from computational investigations, in parts of the phase space where experimental data is hard, dangerous, or expensive to obtain. A prominent materials area where such computational investigations are hard to perform today because of limited accuracy is actinide and lanthanide materials. The Science of Extreme Environment Lab Directed Research and Development project described in this Report has had the aim to cure this accuracy problem. We have focused on the two major factors which would allow for accurate computational investigations of actinide and lanthanide materials: (1) The fully relativistic treatment needed for materials containing heavy atoms, and (2) the needed improved performance of DFT exchange-correlation functionals. We have implemented a fully relativistic treatment based on the Dirac Equation into the LANL code RSPt and we have shown that such a treatment is imperative when calculating properties of materials containing actinides and/or lanthanides. The present standard treatment that only includes some of the relativistic terms is not accurate enough and can even give misleading results. Compared to calculations previously considered state of the art, the Dirac treatment gives a substantial change in equilibrium volume predictions for materials with large spin-orbit coupling. For actinide and lanthanide materials, a Dirac treatment is thus a fundamental requirement in any computational investigation, including those for DFT-based EOS construction. For a full capability, a DFT functional capable of describing strongly correlated systems such as actinide materials need to be developed. Using the previously successful subsystem functional scheme developed by Mattsson et.al., we have created such a functional. In this functional the Harmonic Oscillator Gas is providing the necessary reference system for the strong correlation and localization occurring in actinides. Preliminary testing shows that the new Hao-Armiento-Mattsson (HAM) functional gives a trend towards improved results for the crystalline copper oxide test system we have chosen. This test system exhibits the same exchange-correlation physics as the actinide systems do, but without the relativistic effects, giving access to a pure testing ground for functionals. During the work important insights have been gained. An example is that currently available functionals, contrary to common belief, make large errors in so called hybridization regions where electrons from different ions interact and form new states. Together with the new understanding of functional issues, the Dirac implementation into the RSPt code will permit us to gain more fundamental understanding, both quantitatively and qualitatively, of materials of importance for Sandia and the rest of the Nuclear Weapons complex.

Mattsson, Ann Elisabet

2012-01-01T23:59:59.000Z

299

Electron dynamics in complex environments with real-time time dependent density functional theory in a QM-MM framework  

SciTech Connect (OSTI)

This article presents a time dependent density functional theory (TDDFT) implementation to propagate the Kohn-Sham equations in real time, including the effects of a molecular environment through a Quantum-Mechanics Molecular-Mechanics (QM-MM) hamiltonian. The code delivers an all-electron description employing Gaussian basis functions, and incorporates the Amber force-field in the QM-MM treatment. The most expensive parts of the computation, comprising the commutators between the hamiltonian and the density matrixrequired to propagate the electron dynamics, and the evaluation of the exchange-correlation energy, were migrated to the CUDA platform to run on graphics processing units, which remarkably accelerates the performance of the code. The method was validated by reproducing linear-response TDDFT results for the absorption spectra of several molecular species. Two different schemes were tested to propagate the quantum dynamics: (i) a leap-frog Verlet algorithm, and (ii) the Magnus expansion to first-order. These two approaches were confronted, to find that the Magnus scheme is more efficient by a factor of six in small molecules. Interestingly, the presence of iron was found to seriously limitate the length of the integration time step, due to the high frequencies associated with the core-electrons. This highlights the importance of pseudopotentials to alleviate the cost of the propagation of the inner states when heavy nuclei are present. Finally, the methodology was applied to investigate the shifts induced by the chemical environment on the most intense UV absorption bands of two model systems of general relevance: the formamide molecule in water solution, and the carboxy-heme group in Flavohemoglobin. In both cases, shifts of several nanometers are observed, consistently with the available experimental data.

Morzan, Uriel N.; Ramrez, Francisco F.; Scherlis, Damin A., E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Departamento de Qumica Inorgnica, Analtica y Qumica Fsica/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires (C1428EHA) (Argentina); Oviedo, M. Beln; Snchez, Cristin G. [Departamento de Matemtica y Fsica, Facultad de Ciencias Qumicas, INFIQC, Universidad Nacional de Crdoba, Ciudad Universitaria, X5000HUA Crdoba (Argentina)] [Departamento de Matemtica y Fsica, Facultad de Ciencias Qumicas, INFIQC, Universidad Nacional de Crdoba, Ciudad Universitaria, X5000HUA Crdoba (Argentina); Lebrero, Mariano C. Gonzlez, E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Instituto de Qumica y Fisicoqumica Biolgicas, IQUIFIB, CONICET (Argentina)] [Instituto de Qumica y Fisicoqumica Biolgicas, IQUIFIB, CONICET (Argentina)

2014-04-28T23:59:59.000Z

300

Density functional theory study of chemical sensing on surfaces of single-layer MoS{sub 2} and graphene  

SciTech Connect (OSTI)

In this work, density functional theory (DFT) calculations have been used to investigate chemical sensing on surfaces of single-layer MoS{sub 2} and graphene, considering the adsorption of the chemical compounds triethylamine, acetone, tetrahydrofuran, methanol, 2,4,6-trinitrotoluene, o-nitrotoluene, o-dichlorobenzene, and 1,5-dicholoropentane. Physisorption of the adsorbates on free-standing surfaces was analyzed in detail for optimized material structures, considering various possible adsorption sites. Similar adsorption characteristics for the two surface types were demonstrated, where inclusion of a correction to the DFT functional for London dispersion was shown to be important to capture interactions at the interface of molecular adsorbate and surface. Charge transfer analyses for adsorbed free-standing surfaces generally demonstrated very small effects. However, charge transfer upon inclusion of the underlying SiO{sub 2} substrate rationalized experimental observations for some of the adsorbates considered. A larger intrinsic response for the electron-donor triethylamine adsorbed on MoS{sub 2} as compared to graphene was demonstrated, which may assist in devising chemical sensors for improved sensitivity.

Mehmood, F.; Pachter, R., E-mail: ruth.pachter@us.af.mil [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States)

2014-04-28T23:59:59.000Z

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301

Increasing the applicability of density functional theory. IV. Consequences of ionization-potential improved exchange-correlation potentials  

SciTech Connect (OSTI)

This paper's objective is to create a consistent mean-field based Kohn-Sham (KS) density functional theory (DFT) meaning the functional should not only provide good total energy properties, but also the corresponding KS eigenvalues should be accurate approximations to the vertical ionization potentials (VIPs) of the molecule, as the latter condition attests to the viability of the exchange-correlation potential (V{sub XC}). None of the prominently used DFT approaches show these properties: the optimized effective potential V{sub XC} based ab initio dft does. A local, range-separated hybrid potential cam-QTP-00 is introduced as the basis for a consistent KS DFT approach. The computed VIPs as the negative of KS eigenvalue have a mean absolute error of 0.8 eV for an extensive set of molecule's electron ionizations, including the core. Barrier heights, equilibrium geometries, and magnetic properties obtained from the potential are in good agreement with experiment. A similar accuracy with less computational efforts can be achieved by using a non-variational global hybrid variant of the QTP-00 approach.

Verma, Prakash; Bartlett, Rodney J., E-mail: bartlett@ufl.edu [Quantum Theory Project, University of Florida, Gainesville, Florida 32611 (United States)

2014-05-14T23:59:59.000Z

302

Assessing the density functional theory-based multireference configuration interaction (DFT/MRCI) method for transition metal complexes  

SciTech Connect (OSTI)

We report an assessment of the performance of density functional theory-based multireference configuration interaction (DFT/MRCI) calculations for a set of 3d- and 4d-transition metal (TM) complexes. The DFT/MRCI results are compared to published reference data from reliable high-level multi-configurational ab initio studies. The assessment covers the relative energies of different ground-state minima of the highly correlated CrF{sub 6} complex, the singlet and triplet electronically excited states of seven typical TM complexes (MnO{sub 4}{sup ?}, Cr(CO){sub 6}, [Fe(CN){sub 6}]{sup 4?}, four larger Fe and Ru complexes), and the corresponding electronic spectra (vertical excitation energies and oscillator strengths). It includes comparisons with results from different flavors of time-dependent DFT (TD-DFT) calculations using pure, hybrid, and long-range corrected functionals. The DFT/MRCI method is found to be superior to the tested TD-DFT approaches and is thus recommended for exploring the excited-state properties of TM complexes.

Escudero, Daniel, E-mail: escudero@kofo.mpg.de, E-mail: thiel@kofo.mpg.de; Thiel, Walter, E-mail: escudero@kofo.mpg.de, E-mail: thiel@kofo.mpg.de [Max-Planck-Institut fr Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mlheim an der Ruhr (Germany)] [Max-Planck-Institut fr Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mlheim an der Ruhr (Germany)

2014-05-21T23:59:59.000Z

303

Density-Functional-Theory Calculations of Matter in Strong Magnetic Fields: II. Infinite Chains and Condensed Matter  

E-Print Network [OSTI]

We present new, ab initio calculations of the electronic structure of one-dimensional infinite chains and three-dimensional condensed matter in strong magnetic fields ranging from B=10^12 G to 2x10^15 G, appropriate for observed magnetic neutron stars. At these field strengths, the magnetic forces on the electrons dominate over the Coulomb forces, and to a good approximation the electrons are confined to the ground Landau level. Our calculations are based on the density functional theory, and use a local magnetic exchange-correlation function appropriate in the strong field regime. The band structures of electrons in different Landau orbitals are computed self-consistently. Numerical results of the ground-state energies and electron work functions are given for one-dimensional chains of H, He, C, and Fe. Fitting formulae for the B-dependence of the energies are also provided. For all the field strengths considered in this paper, hydrogen, helium, and carbon chains are found to be bound relative to individual atoms (although for B less than a few x 10^12 G, the relative binding between C and C_infinity is small). Iron chains are significantly bound for B>10^14 G and are weakly bound if at all at B<10^13 G. We also study the cohesive property of three-dimensional condensed matter of H, He, C, and Fe at zero pressure, constructed from interacting chains in a body-centered tetragonal lattice. Such three-dimensional condensed matter is found to be bound relative to individual atoms, with the cohesive energy increasing rapidly with increasing B.

Zach Medin; Dong Lai

2007-01-05T23:59:59.000Z

304

Mixed valency and site-preference chemistry for cerium and its compounds: A predictive density-functional theory study  

SciTech Connect (OSTI)

Cerium and its technologically relevant compounds are examples of anomalous mixed valency, originating from two competing oxidation statesitinerant Ce4+ and localized Ce3+. Under applied stress, anomalous transitions are observed but not well understood. Here we treat mixed valency as an alloy problem involving two valences with competing and numerous site-occupancy configurations. We use density-functional theory with Hubbard U (i.e., DFT+U) to evaluate the effective valence and predict properties, including controlling the valence by pseudoternary alloying. For Ce and its compounds, such as (Ce,La)2(Fe,Co)14B permanent magnets, we find a stable mixed-valent ? state near the spectroscopic value of ?s=3.53. Ce valency in compounds depends on its steric volume and local chemistry. For La doping, Ce valency shifts towards ?-like Ce3+, as expected from steric volume; for Co doping, valency depends on local Ce-site chemistry and steric volume. Our approach captures the key origins of anomalous valency and site-preference chemistry in complex compounds.

Alam, Aftab [Ames Laboratory; Johnson, Duane D. [Ames Laboratory

2014-06-01T23:59:59.000Z

305

"Kohn-Shamification" of the classical density-functional theory of inhomogeneous polar molecular liquids with application to liquid hydrogen chloride  

E-Print Network [OSTI]

The Gordian knot of density-functional theories for classical molecular liquids remains finding an accurate free-energy functional in terms of the densities of the atomic sites of the molecules. Following Kohn and Sham, we show how to solve this problem by considering noninteracting molecules in a set of effective potentials. This shift in perspective leads to an accurate and computationally tractable description in terms of simple three-dimensional functions. We also treat both the linear- and saturation- dielectric responses of polar systems, presenting liquid hydrogen chloride as a case study.

Johannes Lischner; T. A. Arias

2008-06-27T23:59:59.000Z

306

Probing Ligand Effects on the Redox Energies of [4Fe-4S] Clusters Using Broken-Symmetry Density Functional Theory  

SciTech Connect (OSTI)

A central issue in understanding redox properties of iron-sulfur proteins is determining the factors that tune the reduction potentials of the Fe-S clusters. Recently, Solomon and coworkers have shown that the Fe-S bond covalency of protein analogs measured by %L, the percent ligand character of the Fe 3d orbitals, from ligand K-edge X-ray absorption spectroscopy (XAS) correlates with the electrochemical redox potentials. Also, Wang and coworkers have measured electron detachment energies for iron-sulfur clusters without environmental perturbations by gas-phase photoelectron spectroscopy (PES). Here the correlations of the ligand character with redox energy and %L character are examined in [Fe?S?L?]2? clusters with different ligands by broken symmetry density functional theory (BS-DFT) calculations using the B3LYP functional together with PES and XAS experimental results. These gas-phase studies assess ligand effects independently of environmental perturbations and thus provide essential information for computational studies of iron-sulfur proteins. The B3LYP oxidation energies agree well with PES data, and the %L character obtained from natural bond orbital analysis correlates with XAS values, although it systematically underestimates them because of basis set effects. The results show that stronger electron-donating terminal ligands increase %Lt, the percent ligand character from terminal ligands, but decrease %Sb, the percent ligand character from the bridging sulfurs. Because the oxidized orbital has significant Fe-Lt antibonding character, the oxidation energy correlates well with %Lt. However, because the reduced orbital has varying contributions of both Fe-Lt and Fe-Sb antibonding character, the reduction energy does not correlate with either %Lt or %Sb. Overall, BSDFT calculations together with XAS and PES experiments can unravel the complex underlying factors in the redox energy and chemical bonding of the [4Fe-4S] clusters in iron-sulfur proteins.

Niu, Shuqiang; Ichiye, Toshiko

2009-05-14T23:59:59.000Z

307

PdnCO (n ) 1,2): Accurate Ab Initio Bond Energies, Geometries, and Dipole Moments and the Applicability of Density Functional Theory for Fuel Cell Modeling  

E-Print Network [OSTI]

and the Applicability of Density Functional Theory for Fuel Cell Modeling Nathan E. Schultz, Benjamin F. Gherman Form: August 18, 2006 Electrode poisoning by CO is a major concern in fuel cells. As interest. Introduction Several of the most successful fuel cell applications use a Pt anode as a catalyst

Gherman, Benjamin F.

308

A Density Functional Theory Study of the Mechanism of Free Radical Generation in the System Vanadate/PCA/H2O2  

E-Print Network [OSTI]

with H2O2 releases HOO· free radicals and generates V(IV) species, which are capable of generating HOA Density Functional Theory Study of the Mechanism of Free Radical Generation in the System for HOO· generation. It is also found that species containing two pca ligands and an H2O2 molecule do

Bell, Alexis T.

309

L-asparagine crystals with wide gap semiconductor features: Optical absorption measurements and density functional theory computations  

SciTech Connect (OSTI)

Results of optical absorption measurements are presented together with calculated structural, electronic, and optical properties for the anhydrous monoclinic L-asparagine crystal. Density functional theory (DFT) within the generalized gradient approximation (GGA) including dispersion effects (TS, Grimme) was employed to perform the calculations. The optical absorption measurements revealed that the anhydrous monoclinic L-asparagine crystal is a wide band gap material with 4.95 eV main gap energy. DFT-GGA+TS simulations, on the other hand, produced structural parameters in very good agreement with X-ray data. The lattice parameter differences ?a, ?b, ?c between theory and experiment were as small as 0.020, 0.051, and 0.022, respectively. The calculated band gap energy is smaller than the experimental data by about 15%, with a 4.23 eV indirect band gap corresponding to Z???? and Z???? transitions. Three other indirect band gaps of 4.30 eV, 4.32 eV, and 4.36 eV are assigned to ?3 ???, ?1 ???, and ?2 ??? transitions, respectively. ?-sol computations, on the other hand, predict a main band gap of 5.00 eV, just 50 meV above the experimental value. Electronic wavefunctions mainly originating from O 2pcarboxyl, C 2pside chain, and C 2pcarboxyl orbitals contribute most significantly to the highest valence and lowest conduction energy bands, respectively. By varying the lattice parameters from their converged equilibrium values, we show that the unit cell is less stiff along the b direction than for the a and c directions. Effective mass calculations suggest that hole transport behavior is more anisotropic than electron transport, but the mass values allow for some charge mobility except along a direction perpendicular to the molecular layers of L-asparagine which form the crystal, so anhydrous monoclinic L-asparagine crystals could behave as wide gap semiconductors. Finally, the calculations point to a high degree of optical anisotropy for the absorption and complex dielectric function, with more structured curves for incident light polarized along the 100 and 101 directions.

Zanatta, G.; Gottfried, C. [Departamento de Bioqumica, Universidade Federal do Rio Grande do Sul, 90035-003 Porto Alegre-RS (Brazil)] [Departamento de Bioqumica, Universidade Federal do Rio Grande do Sul, 90035-003 Porto Alegre-RS (Brazil); Silva, A. M. [Universidade Estadual do Piau, 64260-000 Piripiri-Pi (Brazil)] [Universidade Estadual do Piau, 64260-000 Piripiri-Pi (Brazil); Caetano, E. W. S., E-mail: ewcaetano@gmail.com [Instituto de Educao, Cincia e Tecnologia do Cear, 60040-531 Fortaleza-CE (Brazil)] [Instituto de Educao, Cincia e Tecnologia do Cear, 60040-531 Fortaleza-CE (Brazil); Sales, F. A. M.; Freire, V. N. [Departamento de Fsica, Universidade Federal do Cear, Caixa Postal 6030, 60455-760 Fortaleza-CE (Brazil)] [Departamento de Fsica, Universidade Federal do Cear, Caixa Postal 6030, 60455-760 Fortaleza-CE (Brazil)

2014-03-28T23:59:59.000Z

310

On the Accuracy of van der Waals Inclusive Density-Functional Theory Exchange-Correlation Functionals for Ice at Ambient and High Pressures  

E-Print Network [OSTI]

Density-functional theory (DFT) has been widely used to study water and ice for at least 20 years. However, the reliability of different DFT exchange-correlation (xc) functionals for water remains a matter of considerable debate. This is particularly true in light of the recent development of DFT based methods that account for van der Waals (vdW) dispersion forces. Here, we report a detailed study with several xc functionals (semi-local, hybrid, and vdW inclusive approaches) on ice Ih and six proton ordered phases of ice. Consistent with our previous study [Phys. Rev. Lett. 107, 185701 (2011)] which showed that vdW forces become increasingly important at high pressures, we find here that all vdW inclusive methods considered improve the relative energies and transition pressures of the high-pressure ice phases compared to those obtained with semi-local or hybrid xc functionals. However, we also find that significant discrepancies between experiment and the vdW inclusive approaches remain in the cohesive properties of the various phases, causing certain phases to be absent from the phase diagram. Therefore, room for improvement in the description of water at ambient and high pressures remains and we suggest that because of the stern test the high pressure ice phases pose they should be used in future benchmark studies of simulation methods for water.

Biswajit Santra; Ji? Klime; Alexandre Tkatchenko; Dario Alf; Ben Slater; Angelos Michaelides; Roberto Car; Matthias Scheffler

2014-08-14T23:59:59.000Z

311

Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems  

SciTech Connect (OSTI)

Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ?{sub ?} and oscillator strengths f{sub ?} for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Lwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Lwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Lwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ?{sub ?}(R) curves along the bond dissociation coordinate R for the molecules LiH, Li{sub 2}, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate.

Meer, R. van; Gritsenko, O. V. [Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands) [Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands); WCU Program, Dep. of Chemistry, Pohang Univ. of Science and Techn., Pohang (Korea, Republic of); Baerends, E. J. [Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands) [Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands); WCU Program, Dep. of Chemistry, Pohang Univ. of Science and Techn., Pohang (Korea, Republic of); Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2014-01-14T23:59:59.000Z

312

Coupled-cluster, Mller Plesset (MP2), Density Fitted Local MP2, and Density Functional Theory Examination of the Energetic and Structural Features of Hydrophobic Solvation: Water and Pentane  

SciTech Connect (OSTI)

The interaction potentials between immiscible polar and non-polar solvents are a major driving force behind the formation of liquid:liquid interfaces. In this work, the interaction energy of waterpentane dimer has been determined using coupled-cluster theory with single double (triple) excitations [CCSD(T)], 2nd order Mller Plesset perturbation theory (MP2), density fitted local MP2 (DF-LMP2), as well as density functional theory using a wide variety of density functionals and several different basis sets. The M05-2X exchange correlation functionals exhibit excellent agreement with CCSD(T) and DF-LMP2 after taking into account basis set superposition error. The gas phase waterpentane interaction energy is found to be quite sensitive to the specific pentane isomer (2,2- dimethylpropane vs. n-pentane) and relative orientation of the monomeric constituents. Subsequent solution phase cluster calculations of 2,2-dimethylpropane and n-pentane solvated by water indicate a positive free energy of solvation that is in good agreement with available experimental data. Structural parameters are quite sensitive to the density functional employed and reflect differences in the two-body interaction energy calculated by each method. In contrast, cluster calculations of pentane solvation of H2O solute are found to be inadequate for describing the organic solvent, likely due to limitations associated with the functionals employed (B3LYP, BHandH, and M05-2X).

Ghadar, Yasaman; Clark, Aurora E.

2012-02-02T23:59:59.000Z

313

Density-dependent covariant energy density functionals  

SciTech Connect (OSTI)

Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.

Lalazissis, G. A. [Physics Department, Aristotle University of Thessaloniki, GR-54124 (Greece)

2012-10-20T23:59:59.000Z

314

Density Functional Theory in Transition-Metal Chemistry: Relative Energies of Low-Lying States of Iron Compounds and the Effect of Spatial Symmetry Breaking  

SciTech Connect (OSTI)

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The ground and lower excited states of Fe2, Fe2 -, and FeO+ were studied using a number of density functional theory (DFT) methods. Specific attention was paid to the relative state energies, the internuclear distances (re), and the harmonic vibrational frequencies (e). A number of factors influencing the calculated values of these properties were examined. These include basis sets, the nature of the density functional chosen, the percentage of Hartree- Fock exchange in the density functional, and constraints on orbital symmetry. A number of different types of generalized gradient approximation (GGA) density functionals (straight GGA, hybrid GGA, meta-GGA, and hybrid meta-GGA) were examined, and it was found that the best results were obtained with hybrid GGA or hybrid meta-GGA functionals that contain nonzero fractions of HF exchange; specifically, the best overall results were obtained with B3LYP, M05, and M06, closely followed by B1LYP. One significant observation was the effect of enforcing symmetry on the orbitals. When a degenerate orbital ( or ) is partially occupied in the 4 excited state of FeO+, reducing the enforced symmetry (from C6v to C4v to C2v) results in a lower energy since these degenerate orbitals are split in the lower symmetries. The results obtained were compared to higher level ab initio results from the literature and to recent PBE+U plane wave results by Kulik et al. (Phys. Rev. Lett. 2006, 97, 103001). It was found that some of the improvements that were afforded by the semiempirical +U correction can also be accomplished by improving the form of the DFT functional and, in one case, by not enforcing high symmetry on the orbitals.

Sorkin, Anastassia; Iron, Mark A.; Truhlar, Donald G.

2008-02-01T23:59:59.000Z

315

The adsorption of h-BN monolayer on the Ni(111) surface studied by density functional theory calculations with a semiempirical long-range dispersion correction  

SciTech Connect (OSTI)

The geometric and spin-resolved electronic structure of a h-BN adsorbed Ni(111) surface has been investigated by density functional theory calculations. Two energy minima (physisorption and chemisorption) are obtained when the dispersive van der Waals correction is included. The geometry of N atom on top site and B atom on fcc site is the most energetically favorable. Strong hybridization with the ferromagnetic Ni substrate induces considerable gap states in the h-BN monolayer. The induced ?* states are spin-polarized.

Sun, X., E-mail: sunx@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Pratt, A. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); York Institute for Materials Research, Department of Physics, University of York, York YO10 5DD (United Kingdom); Li, Z. Y. [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Ohtomo, M.; Sakai, S. [Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Ibaraki 319-1195 (Japan); Yamauchi, Y. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

2014-05-07T23:59:59.000Z

316

Ab initio density functional theory investigation of the structural, electronic and optical properties of Ca{sub 3}Sb{sub 2} in hexagonal and cubic phases  

SciTech Connect (OSTI)

A density functional theory study of structural, electronical and optical properties of Ca{sub 3}Sb{sub 2} compound in hexagonal and cubic phases is presented. In the exchangecorrelation potential, generalized gradient approximation (PBE-GGA) has been used to calculate lattice parameters, bulk modulus, cohesive energy, dielectric function and energy loss spectra. The electronic band structure of this compound has been calculated using the above two approximations as well as another form of PBE-GGA, proposed by Engle and Vosko (EV-GGA). It is found that the hexagonal phase of Ca{sub 3}Sb{sub 2} has an indirect gap in the ??N direction; while in the cubic phase there is a direct-gap at the ? point in the PBE-GGA and EV-GGA. Effects of applying pressure on the band structure of the system studied and optical properties of these systems were calculated. - Graphical abstract: A density functional theory study of structural, electronic and optical properties of Ca{sub 3}Sb{sub 2} compound in hexagonal and cubic phases is presented. Display Omitted - Highlights: Physical properties of Ca{sub 3}Sb{sub 2} in hexagonal and cubic phases are investigated. It is found that the hexagonal phase is an indirect gap semiconductor. Ca{sub 3}Sb{sub 2} is a direct-gap semiconductor at the ? point in the cubic phase. By increasing pressure the semiconducting band gap and anti-symmetry gap are decreased.

Arghavani Nia, Borhan, E-mail: b.arghavani@gmail.com [Department of Physics, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Sedighi, Matin [Department of Physics, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Shahrokhi, Masoud [Young Researchers and Elite Club, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Moradian, Rostam [Nano-Science and Nano-Technology Research Center, Razi University, Kermanshah (Iran, Islamic Republic of); Computational Physics Science Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-1795, Tehran (Iran, Islamic Republic of)

2013-11-15T23:59:59.000Z

317

Simulating one-photon absorption and resonance Raman scattering spectra using analytical excited state energy gradients within time-dependent density functional theory  

SciTech Connect (OSTI)

A parallel implementation of analytical time-dependent density functional theory gra- dients is presented for the quantum chemistry program NWChem. The implementation is based on the Lagrangian approach developed by Furche and Ahlrichs. To validate our implementation, we first calculate the Stokes shifts for a range of organic dye molecules using a diverse set of exchange-correlation functionals (traditional density functionals, global hybrids and range-separated hybrids) followed by simulations of the one-photon absorption and resonance Raman scattering spectrum of the phenoxyl radical, the well-studied dye molecule rhodamine 6G and a molecular host-guest complex (TTF?CBPQT4+). The study of organic dye molecules illustrates that B3LYP and CAM-B3LYP generally give the best agreement with experimentally determined Stokes shifts unless the excited state is a charge transfer state. Absorption, resonance Raman, and fluorescence simulations for the phenoxyl radical indicate that explicit solvation may be required for accurate characterization. For the host-guest complex and rhodamine 6G, it is demonstrated that absorption spectra can be simulated in good agreement with experiment for most exchange-correlation functionals. However, because one-photon absorption spectra generally lack well-resolved vibrational features, resonance Raman simulations are necessary to evaluate the accuracy of the exchange-correlation functional for describing a potential energy surface.

Silverstein, Daniel W.; Govind, Niranjan; van Dam, Hubertus JJ; Jensen, Lasse

2013-12-10T23:59:59.000Z

318

Subsystem Density-Functional Theory as an Effective Tool for Modeling Ground and Excited States, their Dynamics, and Many-Body Interactions  

E-Print Network [OSTI]

Subsystem Density-Functional Theory (DFT) is an emerging technique for calculating the electronic structure of complex molecular and condensed phase systems. In this topical review, we focus on some recent advances in this field related to the computation of condensed phase systems, their excited states, and the evaluation of many-body interactions between the subsystems. As subsystem DFT is in principle an exact theory, any advance in this field can have a dual role. One is the possible applicability of a resulting method in practical calculations. The other is the possibility of shedding light on some quantum-mechanical phenomenon which is more easily treated by subdividing a supersystem into subsystems. An example of the latter is many-body interactions. In the discussion, we present some recent work from our research group as well as some new results, casting them in the current state-of-the-art in this review as comprehensively as possible.

Krishtal, Alisa; Genova, Alessandro; Pavanello, Michele

2015-01-01T23:59:59.000Z

319

Phenomenological Relativistic Energy Density Functionals  

SciTech Connect (OSTI)

The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

Lalazissis, G. A.; Kartzikos, S. [Physics Department, Aristotle University of Thessaloniki (Greece); Niksic, T.; Paar, N.; Vretenar, D. [Physics Department, University of Zagreb (Croatia); Ring, P. [Physics Department, TU Muenchen, Garching (Germany)

2009-08-26T23:59:59.000Z

320

Development of multicomponent hybrid density functional theory with polarizable continuum model for the analysis of nuclear quantum effect and solvent effect on NMR chemical shift  

SciTech Connect (OSTI)

We have developed the multicomponent hybrid density functional theory [MC-(HF+DFT)] method with polarizable continuum model (PCM) for the analysis of molecular properties including both nuclear quantum effect and solvent effect. The chemical shifts and H/D isotope shifts of the picolinic acid N-oxide (PANO) molecule in chloroform and acetonitrile solvents are applied by B3LYP electron exchange-correlation functional for our MC-(HF+DFT) method with PCM (MC-B3LYP/PCM). Our MC-B3LYP/PCM results for PANO are in reasonable agreement with the corresponding experimental chemical shifts and isotope shifts. We further investigated the applicability of our method for acetylacetone in several solvents.

Kanematsu, Yusuke; Tachikawa, Masanori [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)] [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)

2014-04-28T23:59:59.000Z

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321

Spin and orbital magnetism of coinage metal trimers (Cu{sub 3}, Ag{sub 3}, Au{sub 3}): A relativistic density functional theory study  

SciTech Connect (OSTI)

We have demonstrated electronic structure and magnetic properties of Cu{sub 3}, Ag{sub 3} and Au{sub 3} trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21?{sub B} was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.

Afshar, Mahdi [Department of Physics, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)] [Department of Physics, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Sargolzaei, Mohsen [Department of Chemistry, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)] [Department of Chemistry, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)

2013-11-15T23:59:59.000Z

322

A density functional theory study of magneto-electric Jones birefringence of noble gases, furan homologues, and mono-substituted benzenes  

SciTech Connect (OSTI)

We report on the results of a systematic ab initio study of the Jones birefringence of noble gases, of furan homologues, and of monosubstituted benzenes, in the gas phase, with the aim of analyzing the behavior and the trends within a list of systems of varying size and complexity, and of identifying candidates for a combined experimental/theoretical study of the effect. We resort here to analytic linear and nonlinear response functions in the framework of time-dependent density functional theory. A correlation is made between the observable (the Jones constant) and the atomic radius for noble gases, or the permanent electric dipole and a structure/chemical reactivity descriptor as the para Hammett constant for substituted benzenes.

Fahleson, Tobias; Norman, Patrick, E-mail: panor@ifm.liu.se [Department of Physics, Chemistry and Biology, Linkping University, SE-581 83 Linkping (Sweden); Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Universit degli Studi di Trieste, I-34127 Trieste (Italy); Rizzo, Antonio, E-mail: rizzo@ipcf.cnr.it [CNR - Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico Fisici (IPCF-CNR), UOS di Pisa, I-56124 Pisa (Italy); Rikken, Geert L. J. A., E-mail: geert.rikken@lncmi.cnrs.fr [Laboratoire National des Champs Magntiques Intenses, UPR3228, CNRS/INSA/UJF/UPS, Toulouse and Grenoble (France)

2013-11-21T23:59:59.000Z

323

Including screening in van der Waals corrected density functional theory calculations: The case of atoms and small molecules physisorbed on graphene  

SciTech Connect (OSTI)

The Density Functional Theory (DFT)/van der Waals-Quantum Harmonic Oscillator-Wannier function (vdW-QHO-WF) method, recently developed to include the vdW interactions in approximated DFT by combining the quantum harmonic oscillator model with the maximally localized Wannier function technique, is applied to the cases of atoms and small molecules (X=Ar, CO, H{sub 2}, H{sub 2}O) weakly interacting with benzene and with the ideal planar graphene surface. Comparison is also presented with the results obtained by other DFT vdW-corrected schemes, including PBE+D, vdW-DF, vdW-DF2, rVV10, and by the simpler Local Density Approximation (LDA) and semilocal generalized gradient approximation approaches. While for the X-benzene systems all the considered vdW-corrected schemes perform reasonably well, it turns out that an accurate description of the X-graphene interaction requires a proper treatment of many-body contributions and of short-range screening effects, as demonstrated by adopting an improved version of the DFT/vdW-QHO-WF method. We also comment on the widespread attitude of relying on LDA to get a rough description of weakly interacting systems.

Silvestrelli, Pier Luigi; Ambrosetti, Alberto [Dipartimento di Fisica e Astronomia, Universit di Padova, via Marzolo 8, I35131 Padova, Italy and DEMOCRITOS National Simulation Center of the Italian Istituto Officina dei Materiali (IOM) of the Italian National Research Council (CNR), Trieste (Italy)] [Dipartimento di Fisica e Astronomia, Universit di Padova, via Marzolo 8, I35131 Padova, Italy and DEMOCRITOS National Simulation Center of the Italian Istituto Officina dei Materiali (IOM) of the Italian National Research Council (CNR), Trieste (Italy)

2014-03-28T23:59:59.000Z

324

Weighted?density?functional theory calculation of elastic constants for face?centered?cubic and body?centered?cubic hard?sphere crystals  

E-Print Network [OSTI]

The isothermal elastic constants for the face?centered?cubic (fcc) and body?centered?cubic (bcc) hard?sphere crystal are calculated for a range of densities using the modified weighted?density functional of Denton and ...

Laird, Brian Bostian

1992-06-01T23:59:59.000Z

325

Structural and electronic properties of cobalt carbide Co2C and its surface stability: Density functional theory study  

E-Print Network [OSTI]

.V. All rights reserved. 1. Introduction Transition metal carbides (TMCs), typically including all 3 d ele- ments and 4 d/5 d elements of groups 3­6 early transition metals, possess unique physical and chemicalStructural and electronic properties of cobalt carbide Co2C and its surface stability: Density

Li, Weixue

326

Isospin-breaking corrections to superallowed Fermi beta-decay in isospin- and angular-momentum-projected nuclear Density Functional Theory  

E-Print Network [OSTI]

Background: The superallowed beta-decay rates provide stringent constraints on physics beyond the Standard Model of particle physics. To extract crucial information about the electroweak force, small isospin-breaking corrections to the Fermi matrix element of superallowed transitions must be applied. Purpose: We perform systematic calculations of isospin-breaking corrections to superallowed beta-decays and estimate theoretical uncertainties related to the basis truncation, time-odd polarization effects related to the intrinsic symmetry of the underlying Slater determinants, and to the functional parametrization. Methods: We use the self-consistent isospin- and angular-momentum-projected nuclear density functional theory employing two density functionals derived from the density independent Skyrme interaction. Pairing correlations are ignored. Our framework can simultaneously describe various effects that impact matrix elements of the Fermi decay: symmetry breaking, configuration mixing, and long-range Coulomb polarization. Results: The isospin-breaking corrections to the I=0+,T=1 --> I=0+,T=1 pure Fermi transitions are computed for nuclei from A=10 to A=98 and, for the first time, to the Fermi branch of the I,T=1/2 --> I,T=1/2 transitions in mirror nuclei from A=11 to A=49. We carefully analyze various model assumptions impacting theoretical uncertainties of our calculations and provide theoretical error bars on our predictions. Conclusions: The overall agreement with empirical isospin-breaking corrections is very satisfactory. Using computed isospin-breaking corrections we show that the unitarity of the CKM matrix is satisfied with a precision better than 0.1%.

W. Satula; J. Dobaczewski; W. Nazarewicz; T. R. Werner

2012-10-25T23:59:59.000Z

327

Systematic study of nuclear matrix elements in neutrinoless double-beta decay with a beyond mean-field covariant density functional theory  

E-Print Network [OSTI]

We report a systematic study of nuclear matrix elements (NMEs) in neutrinoless double-beta decays with a state-of-the-art beyond mean-field covariant density functional theory. The dynamic effects of particle-number and angular-momentum conservations as well as quadrupole shape fluctuations are taken into account with projections and generator coordinate method for both initial and final nuclei. The full relativistic transition operator is adopted to calculate the NMEs. The present systematic studies show that in most of the cases there is a much better agreement with the previous non-relativistic calculation based on the Gogny force than in the case of the nucleus $^{150}$Nd found in Song et al. [Phys. Rev. C 90, 054309 (2014)]. In particular, we find that the total NMEs can be well approximated by the pure axial-vector coupling term with a considerable reduction of the computational effort.

J. M. Yao; L. S. Song; K. Hagino; P. Ring; J. Meng

2015-01-29T23:59:59.000Z

328

Initial stages of ITO/Si interface formation: In situ x-ray photoelectron spectroscopy measurements upon magnetron sputtering and atomistic modelling using density functional theory  

SciTech Connect (OSTI)

Initial stages of indium tin oxide (ITO) growth on a polished Si substrate upon magnetron sputtering were studied experimentally using in-situ x-ray photoelectron spectroscopy measurements. The presence of pure indium and tin, as well as Si bonded to oxygen at the ITO/Si interface were observed. The experimental observations were compared with several atomistic models of ITO/Si interfaces. A periodic model of the ITO/Si interface was constructed, giving detailed information about the local environment at the interface. Molecular dynamics based on density functional theory was performed, showing how metal-oxygen bonds are broken on behalf of silicon-oxygen bonds. These theoretical results support and provide an explanation for the present as well as previous ex-situ and in-situ experimental observations pointing to the creation of metallic In and Sn along with the growth of SiO{sub x} at the ITO/Si interface.

Lvvik, O. M.; Diplas, S.; Ulyashin, A. [SINTEF Materials and Chemistry, Forskningsveien 1, NO-0314 Oslo (Norway); Romanyuk, A. [University of Basel, Kingelbergstr. 82, CH-4056 Basel (Switzerland)

2014-02-28T23:59:59.000Z

329

Simulating Cl K-edge X-ray absorption spectroscopy in MCl62- (M= U, Np, Pu) complexes and UOCl5- using time-dependent density functional theory  

SciTech Connect (OSTI)

We report simulations of the X-ray absorption near edge structure (XANES) at the Cl K-edge of actinide hexahalides MCl62- (M = U, Np, Pu) and the UOCl5- complex using linear-response time-dependent density functional theory (LR-TDDFT) extended for core excitations. To the best of our knowledge, these are the first calculations of the Cl K-edge spectra of NpCl62- and PuCl62-. In addition, the spectra are simulated with and without the environmental effects of the host crystal as well as ab initio molecular dynamics (AIMD) to capture the dynamical effects due to atomic motion. The calculated spectra are compared with experimental results, where available and the observed trends are discussed.

Govind, Niranjan; De Jong, Wibe A.

2014-02-21T23:59:59.000Z

330

Density functional theory studies on theelectronic, structural, phonon dynamicaland thermo-stability properties of bicarbonates MHCO3, M D Li, Na, K  

SciTech Connect (OSTI)

The structural, electronic, phonon dispersion and thermodynamic properties of MHCO3 (M D Li, Na, K) solids were investigated using density functional theory. The calculated bulk properties for both their ambient and the high-pressure phases are in good agreement with available experimental measurements. Solid phase LiHCO3 has not yet been observed experimentally. We have predicted several possible crystal structures for LiHCO3 using crystallographic database searching and prototype electrostatic ground state modeling. Our total energy and phonon free energy .FPH/ calculations predict that LiHCO3 will be stable under suitable conditions of temperature and partial pressures of CO2 and H2O. Our calculations indicate that the HCO􀀀 3 groups in LiHCO3 and NaHCO3 form an infinite chain structure through O#1; #1; #1;H#1; #1; #1;O hydrogen bonds. In contrast, the HCO􀀀 3 anions form dimers, .HCO􀀀 3 /2, connected through double hydrogen bonds in all phases of KHCO3. Based on density functional perturbation theory, the Born effective charge tensor of each atom type was obtained for all phases of the bicarbonates. Their phonon dispersions with the longitudinal opticaltransverse optical splitting were also investigated. Based on lattice phonon dynamics study, the infrared spectra and the thermodynamic properties of these bicarbonates were obtained. Over the temperature range 0900 K, the FPH and the entropies (S) of MHCO3 (M D Li, Na, K) systems vary as FPH.LiHCO3/ > FPH.NaHCO3/ > FPH.KHCO3/ and S.KHCO3/ > S.NaHCO3/ > S.LiHCO3/, respectively, in agreement with the available experimental data. Analysis of the predicted thermodynamics of the CO2 capture reactions indicates that the carbonate/bicarbonate transition reactions for Na and K could be used for CO2 capture technology, in agreement with experiments.

Duan, Yuhua; Zhang, Bo; Sorescu, Dan C.; Johnson, Karl; Majzoub, Eric H; Luebke, David R.

2012-07-01T23:59:59.000Z

331

Real time density functional simulations of quantum scale conductance  

E-Print Network [OSTI]

We study electronic conductance through single molecules by subjecting a molecular junction to a time dependent potential and propagating the electronic state in real time using time-dependent density functional theory ...

Evans, Jeremy Scott

2009-01-01T23:59:59.000Z

332

Structural defects in epitaxial graphene layers synthesized on C-terminated 4H-SiC (0001{sup }) surfaceTransmission electron microscopy and density functional theory studies  

SciTech Connect (OSTI)

The principal structural defects in graphene multilayers synthesized on the carbon-terminated face of a 4H-SiC (0001{sup }) substrate were investigated using the high-resolution transmission electron microscopy. The analyzed systems include a wide variety of defected structures such as edge dislocations, rotational multilayers, and grain boundaries. It was shown that graphene layers are composed of grains of the size of several nanometres or larger; they differ in a relative rotation by large angles, close to 30. The structure of graphene multilayers results from the synthesis on a SiC (0001{sup }) surface, which proceeds via intensive nucleation of new graphene layers that coalesce under various angles creating an immense orientational disorder. Structural defects are associated with a built-in strain resulting from a lattice mismatch between the SiC substrate and the graphene layers. The density functional theory data show that the high-angular disorder of AB stacked bi-layers is not restoring the hexagonal symmetry of the lattice.

Borysiuk, J., E-mail: jolanta.borysiuk@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotnikw 32/46, 02-668 Warsaw (Poland); Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland); So?tys, J.; Piechota, J. [Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, Pawi?skiego 5a, 02-106 Warsaw (Poland); Krukowski, S. [Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, Pawi?skiego 5a, 02-106 Warsaw (Poland); Institute of High Pressure Physics, Polish Academy of Sciences, Soko?owska 29/37, 01-142 Warsaw (Poland); Baranowski, J. M. [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland); Institute of Electronic Materials Technology, Wlczy?ska 133, 01-919 Warsaw (Poland); St?pniewski, R. [Faculty of Physics, University of Warsaw, Ho?a 69, 00-681 Warsaw (Poland)

2014-02-07T23:59:59.000Z

333

Optimizing minimum free-energy crossing points in solution: Linear-response free energy/spin-flip density functional theory approach  

SciTech Connect (OSTI)

Examining photochemical processes in solution requires understanding the solvent effects on the potential energy profiles near conical intersections (CIs). For that purpose, the CI point in solution is determined as the crossing between nonequilibrium free energy surfaces. In this work, the nonequilibrium free energy is described using the combined method of linear-response free energy and collinear spin-flip time-dependent density functional theory. The proposed approach reveals the solvent effects on the CI geometries of stilbene in an acetonitrile solution and those of thymine in water. Polar acetonitrile decreases the energy difference between the twisted minimum and twisted-pyramidalized CI of stilbene. For thymine in water, the hydrogen bond formation stabilizes significantly the CI puckered at the carbonyl carbon atom. The result is consistent with the recent simulation showing that the reaction path via this geometry is open in water. Therefore, the present method is a promising way of identifying the free-energy crossing points that play an essential role in photochemistry of solvated molecules.

Minezawa, Noriyuki, E-mail: minezawa@fukui.kyoto-u.ac.jp [Fukui Institute for Fundamental Chemistry, Kyoto University, Sakyo-ku, Kyoto 606-8103 (Japan)

2014-10-28T23:59:59.000Z

334

Thermodynamic and Kinetic Properties of Intrinsic Defects and Mg Transmutants in 3C-SiC Determined by Density Functional Theory  

SciTech Connect (OSTI)

Density functional theory (DFT) is used to calculate the thermodynamic and kinetic properties of transmutant Mg in 3C-SiC due to high-energy neutron irradiation associated with the fusion nuclear environment. The formation and binding energies of intrinsic defects, Mg-related defects, and clusters in 3C-SiC are systematically calculated. The minimum energy paths and activation energies during point defect migration and small cluster evolution are studied using a generalized solid-state elastic band (G-SSNEB) method with DFT energy calculations. Stable defect structures and possible defect migration mechanisms are identified. The evolution of binding energies during Mg2Si formation demonstrates that the formation of Mg2Si needs to overcome a critical nucleus size and nucleation barrier. It is also found that a compressive stress field exists around the Mg2Si nucleus. These data are important inputs in meso- and macro-scale modeling and experiments to understand and predict the impact of Mg on phase stability, microstructure evolution, and performance of SiC and SiC-based materials during long-term neutron exposures.

Hu, Shenyang Y.; Setyawan, Wahyu; Van Ginhoven, Renee M.; Jiang, Weilin; Henager, Charles H.; Kurtz, Richard J.

2014-02-20T23:59:59.000Z

335

van der Waals-corrected Density Functional Theory simulation of adsorption processes on transition-metal surfaces: Xe and graphene on Ni(111)  

E-Print Network [OSTI]

The DFT/vdW-WF2s1 method, recently developed to include the van der Waals interactions in the Density Functional Theory and describe adsorption processes on metal surfaces by taking metal-screening effects into account, is applied to the case of the interaction of Xe and graphene with a transition-metal surface, namely Ni(111). In general the adsorption of rare-gas atoms on metal surfaces is important because is prototypical for physisorption processes. Moreover, the interaction of graphene with Ni(111) is of particular interest for practical applications (efficient and large-scale production of high-quality graphene) and, from a theoretical point of view, is particularly challenging, since it can be described by a delicate interplay between chemisorption and physisorption processes. The first-principles simulation of transition metals require particular care also because they can be viewed as intermediate systems between simple metals and insulating crystals. Even in these cases the method performs well as d...

Silvestrelli, Pier Luigi

2015-01-01T23:59:59.000Z

336

Building a Universal Nuclear Energy Density Functional  

SciTech Connect (OSTI)

During the period of Dec. 1 2006 Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei, based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. The long-term vision initiated with UNEDF is to arrive at a comprehensive, quantitative, and unified description of nuclei and their reactions, grounded in the fundamental interactions between the constituent nucleons. We seek to replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that delivers maximum predictive power with well-quantified uncertainties. Specifically, the mission of this project has been three-fold: ? First, to find an optimal energy density functional (EDF) using all our knowledge of the nucleonic Hamiltonian and basic nuclear properties; ? Second, to apply the EDF theory and its extensions to validate the functional using all the available relevant nuclear structure and reaction data; ? Third, to apply the validated theory to properties of interest that cannot be measured, in particular the properties needed for reaction theory.

Carlson, Joe A. [Michigan State University; Furnstahl, Dick; Horoi, Mihai; Lust, Rusty; Nazaewicc, Witek; Ng, Esmond; Thompson, Ian; Vary, James

2012-12-30T23:59:59.000Z

337

Nuclear Energy Density Functionals Constrained by Low-Energy QCD  

E-Print Network [OSTI]

A microscopic framework of nuclear energy density functionals is reviewed, which establishes a direct relation between low-energy QCD and nuclear structure, synthesizing effective field theory methods and principles of density functional theory. Guided by two closely related features of QCD in the low-energy limit: a) in-medium changes of vacuum condensates, and b) spontaneous breaking of chiral symmetry; a relativistic energy density functional is developed and applied in studies of ground-state properties of spherical and deformed nuclei.

Dario Vretenar

2008-02-06T23:59:59.000Z

338

Ni(NiO)/single-walled carbon nanotubes composite: Synthesis of electro-deposition, gas sensing property for NO gas and density functional theory calculation  

SciTech Connect (OSTI)

Graphical abstract: The Ni(NiO)/semiconducting single-walled carbon nanotubes composite collected from the cathode after electro-deposition shows a high sensitivity to low-concentration NO gas at room temperature (18 C). Display Omitted Highlights: ? Ni(NiO) nanoparticles were deposited on semiconducting SWCNTs by electro-deposition. ? Ni(NiO)/semiconducting SWCNTs film shows a high sensitivity to NO gas at 18 C. ?Theoretical calculation reveals electron transfer from SWCNTs to NO via Ni. -- Abstract: Single-walled carbon nanotubes which contains metallic SWCNTs (m-SWCNTs) and semiconducting SWCNTs (s-SWCNTs) have been obtained under electric arc discharge. Their separation can be effectively achieved by the electro-deposition method. The Ni(NiO)/s-SWCNTs composite was found on cathode where Ni was partially oxidized to NiO at ambient condition with Ni(NiO) nanoparticles deposited uniformly on the bundles of SWCNTs. These results were confirmed by Raman spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UVvisNIR and TG characterizations. Furthermore, investigation of the gas sensing property of Ni(NiO)/s-SWCNTs composite film to NO gas at 18 C demonstrated the sensitivity was approximately 5% at the concentration of 97 ppb. Moreover, density functional theory (DFT) calculations were performed to explore the sensing mechanism which suggested the adsorption of NO molecules onto the composite through NNi interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.

Li, Li; Zhang, Guo; Chen, Lei [Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, College of Heilongjiang Province, Heilongjiang University, Harbin 150080 (China)] [Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, College of Heilongjiang Province, Heilongjiang University, Harbin 150080 (China); Bi, Hong-Mei [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)] [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China); Shi, Ke-Ying, E-mail: shikeying2008@yahoo.cn [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)] [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)

2013-02-15T23:59:59.000Z

339

e/a classification of HumeRothery Rhombic Triacontahedron-type approximants based on all-electron density functional theory calculations  

SciTech Connect (OSTI)

There are three key electronic parameters in elucidating the physics behind the HumeRothery electron concentration rule: the square of the Fermi diameter (2kF)2, the square of the critical reciprocal lattice vector and the electron concentration parameter or the number of itinerant electrons per atom e/a. We have reliably determined these three parameters for 10 Rhombic Triacontahedron-type 2/12/12/1 (N?=?680) and 1/11/11/1 (N?=?160162) approximants by making full use of the full-potential linearized augmented plane wave-Fourier band calculations based on all-electron density-functional theory. We revealed that the 2/12/12/1 approximants Al13Mg27Zn45 and Na27Au27Ga31 belong to two different sub-groups classified in terms of equal to 126 and 109 and could explain why they take different e/a values of 2.13 and 1.76, respectively. Among eight 1/11/11/1 approximants Al3Mg4Zn3, Al9Mg8Ag3, Al21Li13Cu6, Ga21Li13Cu6, Na26Au24Ga30, Na26Au37Ge18, Na26Au37Sn18 and Na26Cd40Pb6, the first two, the second two and the last four compounds were classified into three sub-groups with ?=?50, 46 and 42; and were claimed to obey the e/a?=?2.30, 2.102.15 and 1.701.80 rules, respectively.

Mizutani, U.; Inukai, M.; Sato, H.; Zijlstra, E.S.; Lin, Q.

2014-05-16T23:59:59.000Z

340

Ab initio density functional theory study of non-polar (101{sup }0),?(112{sup }0) and semipolar (202{sup }1) GaN surfaces  

SciTech Connect (OSTI)

The atomic structures of non-polar GaN(101{sup }0),?(112{sup }0) and semipolar GaN(202{sup }1),?(202{sup }1{sup }) surfaces were studied using ab initio calculations within density functional theory. The bulk-like truncated (1??1) structure with buckled Ga-N or Ga-Ga dimers was found stable on the non-polar GaN(101{sup }0) surface in agreement with previous works. Ga-N heterodimers were found energetically stable on the GaN(112{sup }0)-(1??1) surface. The formation of vacancies and substitution site defects was found unfavorable for non-polar GaN surfaces. Semipolar GaN(202{sup }1)-(1??1) surface unit cells consist of non-polar (101{sup }0) and semipolar (101{sup }1) nano-facets. The (101{sup }1) nano-facets consist of two-fold coordinated atoms, which form N-N dimers within a (2??1) surface unit cell on a GaN(202{sup }1) surface. Dimers are not formed on the GaN(202{sup }1{sup }) surface. The stability of the surfaces with single (101{sup }0) or (101{sup }1) nano-facets was analyzed. A single non-polar (101{sup }0)-(1??1) nano-facet was found stable on the GaN(202{sup }1) surface, but unstable on the GaN(202{sup }1{sup }) surface. A single (101{sup }1) nano-facet was found unstable. Semipolar GaN surfaces with (202{sup }1) and (202{sup }1{sup }) polarity can be stabilized with a Ga overlayer at Ga-rich experimental conditions.

Mutombo, P.; Romanyuk, O., E-mail: romanyuk@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnick 10, 16200 Prague (Czech Republic)

2014-05-28T23:59:59.000Z

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341

Structural and electronic properties of Au{sub n?x}Pt{sub x} (n = 214; x ? n) clusters: The density functional theory investigation  

SciTech Connect (OSTI)

The structural evolutions and electronic properties of bimetallic Au{sub nx}Pt{sub x} (n = 214; x ? n) clusters are investigated by using the density functional theory (DFT) with the generalized gradient approximation (GGA). The monatomic doping Au{sub n1}Pt clusters are emphasized and compared with the corresponding pristine Au{sub n} clusters. The results reveal that the planar configurations are favored for both Au{sub n1}Pt and Au{sub n} clusters with size up to n = 13, and the former often employ the substitution patterns based on the structures of the latter. The most stable clusters are Au{sub 6} and Au{sub 6}Pt, which adopt regular planar triangle (D{sub 3h}) and hexagon-ring (D{sub 6h}) structures and can be regarded as the preferential building units in designing large clusters. For Pt-rich bimetallic clusters, their structures can be obtained from the substitution of Pt atoms by Au atoms from the Pt{sub n} structures, where Pt atoms assemble together and occupy the center yet Au atoms prefer the apex positions showing a segregation effect. With respect to pristine Au clusters, Au{sub n}Pt clusters exhibit somewhat weaker and less pronounced odd-even oscillations in the highest occupied and lowest unoccupied molecular-orbital gaps (HOMO-LUMO gap), electron affinity (EA), and ionization potential (IP) due to the partially released electron pairing effect. The analyses of electronic structure indicate that Pt atoms in AuPt clusters would delocalize their one 6s and one 5d electrons to contribute the electronic shell closure. The sp-d hybridizations as well as the d-d interactions between the host Au and dopant Pt atoms result in the enhanced stabilities of AuPt clusters.

Yuan, H. K.; Kuang, A. L.; Tian, C. L.; Chen, H., E-mail: chenh@swu.edu.cn [School of Physical Science and Technology, Southwest University, Chongqing, 400715 (China)

2014-03-15T23:59:59.000Z

342

High density effective theory on the lattice  

E-Print Network [OSTI]

Long-range interactions in finite density QCD necessitate a non-perturbative approach in order to reliably map out the key features and spectrum of the QCD phase diagram. However, the complex nature of the fermion determinant in this sector prohibits the use of established Monte Carlo techniques that utilize importance sampling. Whilst significant progress has been made in the low density, high temperature region, this remains a considerable challenge at mid to high density. At large chemical potential, QCD can be approximated using high density effective theory which is free from the sign problem at leading order. We investigate the implementation of this theory on the lattice in conjunction with existing re-weighting techniques.

A. Dougall

2007-10-08T23:59:59.000Z

343

Diffusion of Te vacancy and interstitials of Te, Cl, O, S, P and Sb in CdTe: A density functional theory study  

E-Print Network [OSTI]

Diffusion of Te vacancy and interstitials of Te, Cl, O, S, P and Sb in CdTe: A density functional profiles in CdTe of native, Te adatom and vacancy, and anionic non-native interstitial adatoms P, Sb, O, S B.V. All rights reserved. 1. Introduction Cadmium telluride (CdTe) based thin films have emerged

Khare, Sanjay V.

344

Density functional theory study of the structural, electronic, lattice dynamical, and thermodynamic properties of Li4SiO4 and its capability for CO2 capture  

SciTech Connect (OSTI)

The structural, electronic, lattice dynamical, optical, thermodynamic, and CO{sub 2} capture properties of monoclinic and triclinic phases of Li{sub 4}SiO{sub 4} are investigated by combining density functional theory with phonon lattice dynamics calculations. We found that these two phases have some similarities in their bulk and thermodynamic properties. The calculated bulk modulus and the cohesive energies of these two phases are close to each other. Although both of them are insulators, the monoclinic phase of Li{sub 4}SiO{sub 4} has a direct band gap of 5.24 eV while the triclinic Li{sub 4}SiO{sub 4} phase has an indirect band gap of 4.98 eV. In both phases of Li{sub 4}SiO{sub 4}, the s orbital of O mainly contributes to the lower-energy second valence band (VB{sub 2}) and the p orbitals contribute to the fist valence band (VB{sub 1}) and the conduction bands (CBs). The s orbital of Si mainly contributes to the lower portions of the VB1 and VB{sub 2}, and Si p orbitals mainly contribute to the higher portions of the VB{sub 1} and VB{sub 2}. The s and p orbitals of Li contribute to both VBs and to CBs, and Li p orbitals have a higher contribution than the Li s orbital. There is possibly a phonon soft mode existing in triclinic {gamma}-Li{sub 4}SiO{sub 4}; in the monoclinic Li{sub 4}SiO{sub 4}, there are three phonon soft modes, which correspond to the one type of Li disordered over a few sites. Their LO-TO splitting indicates that both phases of Li{sub 4}SiO{sub 4} are polar anisotropic materials. The calculated infrared absorption spectra for LO and TO modes are different for these two phases of Li{sub 4}SiO{sub 4}. The calculated relationships of the chemical potential versus temperature and CO{sub 2} pressure for reaction of Li{sub 4}SiO{sub 4} with CO{sub 2} shows that Li{sub 4}SiO{sub 4} could be a good candidate for a high-temperature CO{sub 2} sorbent while used for postcombustion capture technology.

Duan, Yuhua; Parlinski, K.

2011-01-01T23:59:59.000Z

345

Hydrogen adsorption on graphene and coronene: A van der Waals density functional study.  

E-Print Network [OSTI]

??This thesis investigates hydrogen adsorption on graphene and coronene within the framework of density functional theory. The new nonlocal van der Waals density functional (vdW-DF) (more)

Varenius, Eskil

2011-01-01T23:59:59.000Z

346

Density functional theory study on the interstitial chemical shifts of main-group-element centered hexazirconium halide clusters; synthetic control of speciation in [(Zr6ZCl12)] (Z = B, C)-based mixed ligand complexes  

E-Print Network [OSTI]

. For carbide-, boride-, and nitride-centered carbonyl- ligated clusters of the later transition metals, such exceptional chemical shifts have also been observed and are quite comparable to data for hexazirconium clusters.79-86 A number of correlative... make the main contributions to paramagnetic shielding. Kaupp calculated 13C chemical shift tensors for interstitial carbides of a series of transition metal carbonyl clusters using sum-over-states density functional perturbation theory (SOS-DFPT)90...

Shen, Jingyi

2005-08-29T23:59:59.000Z

347

The density of states approach for the simulation of finite density quantum field theories  

E-Print Network [OSTI]

Finite density quantum field theories have evaded first principle Monte-Carlo simulations due to the notorious sign-problem. The partition function of such theories appears as the Fourier transform of the generalised density-of-states, which is the probability distribution of the imaginary part of the action. With the advent of Wang-Landau type simulation techniques and recent advances, the density-of-states can be calculated over many hundreds of orders of magnitude. Current research addresses the question whether the achieved precision is high enough to reliably extract the finite density partition function, which is exponentially suppressed with the volume. In my talk, I review the state-of-play for the high precision calculations of the density-of-states as well as the recent progress for obtaining reliable results from highly oscillating integrals. I will review recent progress for the $Z_3$ quantum field theory for which results can be obtained from the simulation of the dual theory, which appears to free of a sign problem.

K. Langfeld; B. Lucini; A. Rago; R. Pellegrini; L. Bongiovanni

2015-03-02T23:59:59.000Z

348

Testing the kinetic energy functional: Kinetic energy density as a density functional  

E-Print Network [OSTI]

is to the exchange-correlation energy as a functional of the density. A large part of the total energy, the kinetic contexts. For finite systems these forms integrate to the same global ki- netic energy, but they differTesting the kinetic energy functional: Kinetic energy density as a density functional Eunji Sim

Burke, Kieron

349

Universal Nuclear Energy Density Functional  

SciTech Connect (OSTI)

An understanding of the properties of atomic nuclei is crucial for a complete nuclear theory, for element formation, for properties of stars, and for present and future energy and defense applications. During the period of Dec. 1 2006 Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei, based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. Until recently such an undertaking was hard to imagine, and even at the present time such an ambitious endeavor would be far beyond what a single researcher or a traditional research group could carry out.

Carlson, Joseph; Furnstahl, Richard; Horoi, Mihai; Lusk, Rusty; Nazarewicz, Witold; Ng, Esmond; Thompson, Ian; Vary, James

2012-12-01T23:59:59.000Z

350

Instabilities in the Nuclear Energy Density Functional  

E-Print Network [OSTI]

In the field of Energy Density Functionals (EDF) used in nuclear structure and dynamics, one of the unsolved issues is the stability of the functional. Numerical issues aside, some EDFs are unstable with respect to particular perturbations of the nuclear ground-state density. The aim of this contribution is to raise questions about the origin and nature of these instabilities, the techniques used to diagnose and prevent them, and the domain of density functions in which one should expect a nuclear EDF to be stable.

M. Kortelainen; T. Lesinski

2010-02-05T23:59:59.000Z

351

Energy Density Functional for Nuclei and Neutron Stars  

SciTech Connect (OSTI)

Background: Recent observational data on neutron star masses and radii provide stringent constraints on the equation of state of neutron rich matter [ Annu. Rev. Nucl. Part. Sci. 62 485 (2012)]. Purpose: We aim to develop a nuclear energy density functional that can be simultaneously applied to finite nuclei and neutron stars. Methods: We use the self-consistent nuclear density functional theory (DFT) with Skyrme energy density functionals and covariance analysis to assess correlations between observables for finite nuclei and neutron stars. In a first step two energy functionals a high density energy functional giving reasonable neutron properties, and a low density functional fitted to nuclear properties are matched. In a second step, we optimize a new functional using exactly the same protocol as in earlier studies pertaining to nuclei but now including neutron star data. This allows direct comparisons of performance of the new functional relative to the standard one. Results: The new functional TOV-min yields results for nuclear bulk properties (energy, rms radius, diffraction radius, and surface thickness) that are of the same quality as those obtained with the established Skyrme functionals, including SV-min. When comparing SV-min and TOV-min, isoscalar nuclear matter indicators vary slightly while isovector properties are changed considerably. We discuss neutron skins, dipole polarizability, separation energies of the heaviest elements, and proton and neutron drip lines. We confirm a correlation between the neutron skin of 208Pb and the neutron star radius. Conclusions: We demonstrate that standard energy density functionals optimized to nuclear data do not carry information on the expected maximum neutron star mass, and that predictions can only be made within an extremely broad uncertainty band. For atomic nuclei, the new functional TOV-min performs at least as well as the standard nuclear functionals, but it also reproduces expected neutron star data within assumed error bands. This functional is expected to yield more reliable predictions in the region of very neutron rich heavy nuclei.

Erler, J. [UTK/ORNL/German Cancer Research Center-Heidelberg; Horowitz, C. J. [UTK/ORNL/Indiana University; Nazarewicz, Witold [UTK/ORNL/University of Warsaw; Rafalski, M. [UTK/ORNL; Reinhard, P.-G. [Universitat Erlangen, Germany

2013-01-01T23:59:59.000Z

352

Time-dependent density-functional theory for molecular processes in strong fields: Study of multiphoton processes and dynamical response of individual valence electrons of N2 in intense laser fields  

E-Print Network [OSTI]

in the exchange ~x!- only limit. In the latter approach @1#, theTime-dependent density-functional theor Study of multiphoton processes and dynam of N2 in inten Xi Chu and Department of Chemistry, University of Kansas, and Kansas Ce ~Received 30 July 2001; pu We...-I CHU PHYSICAL REVIEW A 64 0634041sg 21su 22sg 22su 21pu 43sg 2 . According to the valence bond theory, this molecule has a triple bond formed with 3sg and 1pu electrons. The 3sg orbital is parallel to the internuclear axis and the two degen- erate 1pu...

Chu, Xi; Chu, Shih-I

2001-11-14T23:59:59.000Z

353

Energy density functional for nuclei and neutron stars  

E-Print Network [OSTI]

We aim to develop a nuclear energy density functional that can be simultaneously applied to finite nuclei and neutron stars. We use the self-consistent nuclear density functional theory (DFT) with Skyrme energy density functionals and covariance analysis to assess correlations between observables for finite nuclei and neutron stars. In a first step two energy functionals -- a high density energy functional giving reasonable neutron properties, and a low density functional fitted to nuclear properties -- are matched. In a second step, we optimize a new functional using exactly the same protocol as in earlier studies pertaining to nuclei but now including neutron star data. This allows direct comparisons of performance of the new functional relative to the standard one. The new functional TOV-min yields results for nuclear bulk properties (energy, r.m.s. radius, diffraction radius, surface thickness) that are of the same quality as those obtained with the established Skyrme functionals, including SV-min. When comparing SV-min and TOV-min, isoscalar nuclear matter indicators vary slightly while isovector properties are changed considerably. We discuss neutron skins, dipole polarizability, separation energies of the heaviest elements, and proton and neutron drip lines. We confirm a correlation between the neutron skin of $^{208}$Pb and the neutron star radius. We demonstrate that standard energy density functionals optimized to nuclear data do not carry information on the expected maximum neutron star mass, and that predictions can only be made within an extremely broad uncertainty band. For atomic nuclei, the new functional TOV-min performs at least as well as the standard nuclear functionals, but it also reproduces expected neutron star data within assumed error bands.

J. Erler; C. J. Horowitz; W. Nazarewicz; M. Rafalski; P. -G. Reinhard

2012-11-27T23:59:59.000Z

354

Stretched hydrogen molecule from a constrained-search density-functional perspective  

SciTech Connect (OSTI)

Constrained-search density functional theory gives valuable insights into the fundamentals of density functional theory. It provides exact results and bounds on the ground- and excited-state density functionals. An important advantage of the theory is that it gives guidance in the construction of functionals. Here they engage constrained search theory to explore issues associated with the functional behavior of 'stretched bonds' in molecular hydrogen. A constrained search is performed with familiar valence bond wavefunctions ordinarily used to describe molecular hydrogen. The effective, one-electron hamiltonian is computed and compared to the corresponding uncorrelated, Hartree-Fock effective hamiltonian. Analysis of the functional suggests the need to construct different functionals for the same density and to allow a competition among these functions. As a result the correlation energy functional is composed explicitly of energy gaps from the different functionals.

Valone, Steven M [Los Alamos National Laboratory; Levy, Mel [DIKE UNIV.

2009-01-01T23:59:59.000Z

355

Ab initio studies of 1,3,5,7-tetranitro-1,3,5,7-tetrazocine/1,3-dimethyl-2-imidazolidinone cocrystal under high pressure using dispersion corrected density functional theory  

SciTech Connect (OSTI)

A detailed study of structural, electronic, and thermodynamic properties of 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)/1,3-dimethyl-2-imidazolidinone (DMI) cocrystal under the hydrostatic pressure of 0100?GPa was performed by using dispersion-corrected density functional theory (DFT-D) method. The calculated crystal structure is in reasonable agreement with the experimental data at the ambient pressure. Based on the analysis of lattice constants, bond lengths, bond angles, and dihedral angles under compression, it is found that HMX molecules in HMX/DMI cocrystal are seriously distorted. In addition, as the pressure increases, the band gap decreases gradually, which suggests that HMX/DMI cocrystal is becoming more metallic. Some important intermolecular interactions between HMX and DMI are also observed in the density of states spectrum. Finally, its thermodynamic properties were characterized, and the results show that HMX/DMI cocrystal is more easily formed in the low pressure.

Gu, Bang-Ming [Institute of Applied Physics, Zhejiang Wanli University, 8 Qianhu South Road, Ningbo 315101 (China); Lin, He; Zhu, Shun-Guan, E-mail: zhusguan@yahoo.com [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China)

2014-04-14T23:59:59.000Z

356

BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL (UNEDF)  

SciTech Connect (OSTI)

The long-term vision initiated with UNEDF is to arrive at a comprehensive, quantitative, and unified description of nuclei and their reactions, grounded in the fundamental interactions between the constituent nucleons. We seek to replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that delivers maximum predictive power with well-quantified uncertainties. Specifically, the mission of this project has been three-fold: First, to find an optimal energy density functional (EDF) using all our knowledge of the nucleonic Hamiltonian and basic nuclear properties. Second, to apply the EDF theory and its extensions to validate the functional using all the available relevant nuclear structure and reaction data. Third, to apply the validated theory to properties of interest that cannot be measured, in particular the properties needed for reaction theory.

Nazarewicz, Witold

2012-07-01T23:59:59.000Z

357

Hybrid density functional calculations of redox potentials and formation energies of transition metal compounds  

E-Print Network [OSTI]

We compare the accuracy of conventional semilocal density functional theory (DFT), the DFT+U method, and the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional for structural parameters, redox reaction energies, and formation ...

Ceder, Gerbrand

358

RICE UNIVERSITY Screened Coulomb Hybrid Density Functionals  

E-Print Network [OSTI]

in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved, Thesis Committee-Scuseria-Ernzerhof (HSE) screened Coulomb hybrid density functional is designed to produce exchange energies comparable to traditional hybrids while only using the short range, screened HF exchange. #12;The accuracy of the HSE

Scuseria, Gustavo E.

359

Configuration Interactions Constrained by Energy Density Functionals  

E-Print Network [OSTI]

A new method for constructing a Hamiltonian for configuration interaction calculations with constraints to energies of spherical configurations obtained with energy-density-functional (EDF) methods is presented. This results in a unified model that reproduced the EDF binding-energy in the limit of single-Slater determinants, but can also be used for obtaining energy spectra and correlation energies with renormalized nucleon-nucleon interactions. The three-body and/or density-dependent terms that are necessary for good nuclear saturation properties are contained in the EDF. Applications to binding energies and spectra of nuclei in the region above 208Pb are given.

B. Alex Brown; Angelo Signoracci; Morten Hjorth-Jensen

2010-09-24T23:59:59.000Z

360

Density functional theory investigation of the electronic structure and thermoelectric properties of layered MoS{sub 2}, MoSe{sub 2} and their mixed-layer compound  

SciTech Connect (OSTI)

First principles density functional theory calculations were carried out for the 2H-MoQ{sub 2} (Q=S and Se) and their hypothetical mixed-layer compound. Due to the different electronegativities of S and Se atoms on MoQ{sub 2}, the band gap size could be adjusted in mixed-layer compound MoS{sub 2}/MoSe{sub 2}. Also, the indirect band gap in pure MoQ{sub 2} compounds is changed to the pseudo direct band gap in mixed-layer MoS{sub 2}/MoSe{sub 2} which is similar to the monolayer compound. The layer mixing enhances the thermoelectric properties because of the increased density of states around the Fermi level and the decreased band gap size. Therefore, we suggest that this layer mixing approach should be regarded as a useful way to modulate their electronic structures and to improve their thermoelectric properties. -- Graphical abstract: On the basis of density functional calculations we predict that the mixed-layer compounds 2H-MoS{sub 2}/2H-MoSe{sub 2}, in which two different layers 2H-MoS{sub 2} and 2H-MoSe{sub 2}, have enhanced thermoelectric properties because of the increased density of states around the Fermi level and the decreased band gap size. Highlights: We explored a way of improving TE properties of 2H-MoQ{sub 2} on DFT methods. The mixed-layer compounds MoS{sub 2}/MoSe{sub 2} have enhanced thermoelectric properties. This is caused by modulated electronic structure of mixed layer compound. Layer mixing approach should be regarded as a useful way to improve TE properties.

Lee, Changhoon; Hong, Jisook [Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Lee, Wang Ro [Faculty of Liberal Education, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Dae Yeon [Agency for Defense Development (ADD), Chinhae, Kyungnam 645-600 (Korea, Republic of); Shim, Ji Hoon, E-mail: jhshim@postech.ac.kr [Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Divisions of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2014-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
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361

Electronic and thermoelectric properties of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} computed with density functional theory with on-site Coulomb interaction correction  

SciTech Connect (OSTI)

The electronic properties and Seebeck coefficients of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} are computed using Density Functional Theory with on-site Coulomb interaction correction. We found that the Seebeck coefficients of Ce{sub 3}Te{sub 4} and La{sub 3}Te{sub 4} are almost equal at temperatures larger than the Curie temperature of Ce{sub 3}Te{sub 4}, and in good agreement with the measurements reported by May et al. [Phys. Rev. B 86, 035135 (2012)]. At temperatures below the Curie temperature, the Seebeck coefficient of Ce{sub 3}Te{sub 4} increases due to the ferromagnetic ordering, which leads the f-electron of Ce to contribute to the Seebeck coefficient in the relevant range of electron concentration.

Vo, Trinh; Allmen, Paul von; Huang, Chen-Kuo; Ma, James; Bux, Sabah; Fleurial, Jean-Pierre [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

2014-10-07T23:59:59.000Z

362

On the phase diagram of water with density functional theory potentials: the melting temperature of Ice I-h with the Perdew-Burke-Ernzerhof and Becke-Lee-Yang-Parr functionals  

SciTech Connect (OSTI)

The melting temperature (Tm) of ice Ih was determined from constant enthalphy (NPH) Born-Oppenheimer Molecular Dynamics (BOMD) simulations to be 4173 K for the Perdew-Burke-Ernzerhof (PBE) and 4114 K for the Becke-Lee-Yang-Parr (BLYP) density functionals using a coexisting ice (Ih)-liquid phase at constant pressures of P = 2,500 and 10,000 bar and a density ? = 1 g/cm3, respectively. This suggests that ambient condition simulations at ? = 1 g/cm3 will rather describe a supercooled state that is overstructured when compared to liquid water. This work was supported by the US Department of Energy Office of Basic Energy Sciences' Chemical Sciences program. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Yoo, Soohaeng; Zeng, Xiao Cheng; Xantheas, Sotiris S.

2009-06-11T23:59:59.000Z

363

Building A Universal Nuclear Energy Density Functional (UNEDF)  

SciTech Connect (OSTI)

During the period of Dec. 1 2006 ?? Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei, based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. The long-term vision initiated with UNEDF is to arrive at a comprehensive, quantitative, and unified description of nuclei and their reactions, grounded in the fundamental interactions between the constituent nucleons. We seek to replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that delivers maximum predictive power with well-quantified uncertainties. Specifically, the mission of this project has been three-fold: first, to find an optimal energy density functional (EDF) using all our knowledge of the nucleonic Hamiltonian and basic nuclear properties; second, to apply the EDF theory and its extensions to validate the functional using all the available relevant nuclear structure and reaction data; third, to apply the validated theory to properties of interest that cannot be measured, in particular the properties needed for reaction theory. The main physics areas of UNEDF, defined at the beginning of the project, were: ab initio structure; ab initio functionals; DFT applications; DFT extensions; reactions.

Carlson, Joe, Los Alamos National Laboratory, Los Alamos, NM; Furnstahl, Dick, Ohio State University, Columbus, OH; Horoi, Mihai, Central Michigan University, Mount Pleasant, MI; Lusk, Rusty, Argonne National Laboratory, Argonne, IL; Nazarewicz, Witek, University of Tennessee, Knoxville, TN; Ng, Esmond, Berkeley National Laboratory, Berkeley, CA; Thompson, Ian, Lawrence Livermore National Laboratory, Livermore, CA; Vary, James, Iowa State University, Ames, Iowa

2012-09-30T23:59:59.000Z

364

Comparison between Gaussian-type orbitals and plane wave ab initio density functional theory modeling of layer silicates: Talc [Mg{sub 3}Si{sub 4}O{sub 10}(OH){sub 2}] as model system  

SciTech Connect (OSTI)

The quantum chemical characterization of solid state systems is conducted with many different approaches, among which the adoption of periodic boundary conditions to deal with three-dimensional infinite condensed systems. This method, coupled to the Density Functional Theory (DFT), has been proved successful in simulating a huge variety of solids. Only in relatively recent years this ab initio quantum-mechanic approach has been used for the investigation of layer silicate structures and minerals. In the present work, a systematic comparison of different DFT functionals (GGA-PBEsol and hybrid B3LYP) and basis sets (plane waves and all-electron Gaussian-type orbitals) on the geometry, energy, and phonon properties of a model layer silicate, talc [Mg{sub 3}Si{sub 4}O{sub 10}(OH){sub 2}], is presented. Long range dispersion is taken into account by DFT+D method. Results are in agreement with experimental data reported in literature, with minimal deviation given by the GTO/B3LYP-D* method regarding both axial lattice parameters and interaction energy and by PW/PBE-D for the unit-cell volume and angular values. All the considered methods adequately describe the experimental talc infrared spectrum.

Ulian, Gianfranco; Valdr, Giovanni, E-mail: giovanni.valdre@unibo.it [Dipartimento di Scienze Biologiche e Geologico-Ambientali, Centro di Ricerca Interdisciplinare di Biomineralogia, Cristallografia e Biomateriali, Universit di Bologna Alma Mater Studiorum Piazza di Porta San Donato 1, 40126 Bologna (Italy)] [Dipartimento di Scienze Biologiche e Geologico-Ambientali, Centro di Ricerca Interdisciplinare di Biomineralogia, Cristallografia e Biomateriali, Universit di Bologna Alma Mater Studiorum Piazza di Porta San Donato 1, 40126 Bologna (Italy); Tosoni, Sergio [Departament de Qumica Fsica and Institut de Qumica Terica i Computacional (IQTCUB), Universitat de Barcelona, C/ Mart i Franqus 1, E-08028 Barcelona (Spain)] [Departament de Qumica Fsica and Institut de Qumica Terica i Computacional (IQTCUB), Universitat de Barcelona, C/ Mart i Franqus 1, E-08028 Barcelona (Spain)

2013-11-28T23:59:59.000Z

365

SURFACE SYMMETRY ENERGY OF NUCLEAR ENERGY DENSITY FUNCTIONALS  

SciTech Connect (OSTI)

We study the bulk deformation properties of the Skyrme nuclear energy density functionals. Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band-heads in Hg and Pb isotopes, and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear energy density functionals. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface-symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

Nikolov, N; Schunck, N; Nazarewicz, W; Bender, M; Pei, J

2010-12-20T23:59:59.000Z

366

X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes  

SciTech Connect (OSTI)

Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

Dey, Abhishek; Hocking, Rosalie K.; /Stanford U., Chem. Dept.; Larsen, Peter; Borovik, Andrew S.; /Kansas U.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC,

2006-09-27T23:59:59.000Z

367

Density functional theory study of the interaction of vinyl radical, ethyne, and ethene with benzene, aimed to define an affordable computational level to investigate stability trends in large van der Waals complexes  

SciTech Connect (OSTI)

Our purpose is to identify a computational level sufficiently dependable and affordable to assess trends in the interaction of a variety of radical or closed shell unsaturated hydro-carbons A adsorbed on soot platelet models B. These systems, of environmental interest, would unavoidably have rather large sizes, thus prompting to explore in this paper the performances of relatively low-level computational methods and compare them with higher-level reference results. To this end, the interaction of three complexes between non-polar species, vinyl radical, ethyne, or ethene (A) with benzene (B) is studied, since these species, involved themselves in growth processes of polycyclic aromatic hydrocarbons (PAHs) and soot particles, are small enough to allow high-level reference calculations of the interaction energy ?E{sub AB}. Counterpoise-corrected interaction energies ?E{sub AB} are used at all stages. (1) Density Functional Theory (DFT) unconstrained optimizations of the A?B complexes are carried out, using the B3LYP-D, ?B97X-D, and M06-2X functionals, with six basis sets: 6-31G(d), 6-311 (2d,p), and 6-311++G(3df,3pd); aug-cc-pVDZ and aug-cc-pVTZ; N07T. (2) Then, unconstrained optimizations by Mller-Plesset second order Perturbation Theory (MP2), with each basis set, allow subsequent single point Coupled Cluster Singles Doubles and perturbative estimate of the Triples energy computations with the same basis sets [CCSD(T)//MP2]. (3) Based on an additivity assumption of (i) the estimated MP2 energy at the complete basis set limit [E{sub MP2/CBS}] and (ii) the higher-order correlation energy effects in passing from MP2 to CCSD(T) at the aug-cc-pVTZ basis set, ?E{sub CC-MP}, a CCSD(T)/CBS estimate is obtained and taken as a computational energy reference. At DFT, variations in ?E{sub AB} with basis set are not large for the title molecules, and the three functionals perform rather satisfactorily even with rather small basis sets [6-31G(d) and N07T], exhibiting deviation from the computational reference of less than 1 kcal mol{sup ?1}. The zero-point vibrational energy corrected estimates ?(E{sub AB}+ZPE), obtained with the three functionals and the 6-31G(d) and N07T basis sets, are compared with experimental D{sub 0} measures, when available. In particular, this comparison is finally extended to the naphthalene and coronene dimers and to three ??? associations of different PAHs (R, made by 10, 16, or 24 C atoms) and P (80 C atoms)

Maranzana, Andrea, E-mail: andrea.maranzana@unito.it, E-mail: anna.giordana@hotmail.com, E-mail: vincenzo.barone@sns.it, E-mail: mauro.causa@unina.it, E-mail: mipavone@unina.it; Giordana, Anna, E-mail: andrea.maranzana@unito.it, E-mail: anna.giordana@hotmail.com, E-mail: vincenzo.barone@sns.it, E-mail: mauro.causa@unina.it, E-mail: mipavone@unina.it; Indarto, Antonius, E-mail: antonius.indarto@che.itb.ac.id; Tonachini, Glauco, E-mail: glauco.tonachini@unito.it [Dipartimento di Chimica, Universit di Torino, Corso Massimo DAzeglio 48, I-10125 Torino (Italy)] [Dipartimento di Chimica, Universit di Torino, Corso Massimo DAzeglio 48, I-10125 Torino (Italy); Barone, Vincenzo, E-mail: andrea.maranzana@unito.it, E-mail: anna.giordana@hotmail.com, E-mail: vincenzo.barone@sns.it, E-mail: mauro.causa@unina.it, E-mail: mipavone@unina.it [Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa (Italy)] [Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa (Italy); Caus, Mauro, E-mail: andrea.maranzana@unito.it, E-mail: anna.giordana@hotmail.com, E-mail: vincenzo.barone@sns.it, E-mail: mauro.causa@unina.it, E-mail: mipavone@unina.it [Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Universit di Napoli Federico II, Via Cintia, 80126 Napoli (Italy)] [Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Universit di Napoli Federico II, Via Cintia, 80126 Napoli (Italy); Pavone, Michele, E-mail: andrea.maranzana@unito.it, E-mail: anna.giordana@hotmail.com, E-mail: vincenzo.barone@sns.it, E-mail: mauro.causa@unina.it, E-mail: mipavone@unina.it [Dipartimento di Scienze Chimiche, Universit di Napoli Federico II, Complesso Universitario di Monte SantAngelo, Via Cintia, I-80126 Napoli (Italy)] [Dipartimento di Scienze Chimiche, Universit di Napoli Federico II, Complesso Universitario di Monte SantAngelo, Via Cintia, I-80126 Napoli (Italy)

2013-12-28T23:59:59.000Z

368

JOURNAL DE PHYSIQUE Colloque C5, supplment au n 5, Tome 40, Mai 1979, page C5-83 Density functional theory of f-band metals : lanthanum, cerium and thorium C1  

E-Print Network [OSTI]

functional theory of f-band metals : lanthanum, cerium and thorium C1 ) D. Glotzel Institut fur cérium et du thorium à l'aide de la méthode « linear muffin tin orbital » (LMTO) et de l'approximation de centered cubic lanthanum, cerium and thorium have been performed using the linear muffin tin orbital (LMTO

Paris-Sud XI, Université de

369

Density Functional Study of the Structure, Stability and Oxygen...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Study of the Structure, Stability and Oxygen Reduction Activity of Ultrathin Platinum Nanowires. Density Functional Study of the Structure, Stability and Oxygen Reduction Activity...

370

Free energies, vacancy concentrations and density distribution anisotropies in hard--sphere crystals: A combined density functional and simulation study  

E-Print Network [OSTI]

We perform a comparative study of the free energies and the density distributions in hard sphere crystals using Monte Carlo simulations and density functional theory (employing Fundamental Measure functionals). Using a recently introduced technique (Schilling and Schmid, J. Chem. Phys 131, 231102 (2009)) we obtain crystal free energies to a high precision. The free energies from Fundamental Measure theory are in good agreement with the simulation results and demonstrate the applicability of these functionals to the treatment of other problems involving crystallization. The agreement between FMT and simulations on the level of the free energies is also reflected in the density distributions around single lattice sites. Overall, the peak widths and anisotropy signs for different lattice directions agree, however, it is found that Fundamental Measure theory gives slightly narrower peaks with more anisotropy than seen in the simulations. Among the three types of Fundamental Measure functionals studied, only the White Bear II functional (Hansen-Goos and Roth, J. Phys.: Condens. Matter 18, 8413 (2006)) exhibits sensible results for the equilibrium vacancy concentration and a physical behavior of the chemical potential in crystals constrained by a fixed vacancy concentration.

M. Oettel; S. Goerig; A. Haertel; H. Loewen; M. Radu; T. Schilling

2010-09-03T23:59:59.000Z

371

Adsorption of acetonitrile (CH{sub 3}CN) on Si(111)-7x7 at room temperature studied by synchrotron radiation core-level spectroscopies and excited-state density functional theory calculations  

SciTech Connect (OSTI)

The room temperature adsorption of acetonitrile (CH{sub 3}-C{identical_to}N) on Si(111)-7x7 is examined by synchrotron radiation N 1s x-ray photoemission and x-ray absorption spectroscopies. The experimental spectroscopic data point to multiple adsorption geometries. Candidate structures are optimized using density functional theory (DFT), the surface being simulated by silicon clusters encompassing one (adjacent) adatom-rest atom pair. This is followed by the DFT calculation of electron transition energies and cross sections. The comparison of theoretical spectra with experimental ones indicates that the molecule is adsorbed on the surface under two forms, a nondissociated geometry (an sp{sup 2}-hybridized CN) and a dissociated one (leading to a pendent sp-hybridized CN). In the nondissociative mode, the molecule bridges an adatom-rest atom pair. For bridge-type models, the discussion of the core-excited state calculations is focussed on the so-called silicon-molecule mixed-state transitions that strongly depend on the breaking or not of the adatom backbonds and on the attachment of the nitrogen end either to the adatom or to the rest atom. Concerning the dissociated state, the CH bond cleavage leads to a cyanomethyl (Si-CH{sub 2}-CN) plus a silicon monohydride, which accounts for the spectroscopic evidence of a free C{identical_to}N group (we do not find at 300 K any spectroscopic evidence for a C{identical_to}N group datively bonded to a silicon atom via its nitrogen lone pair). Therefore the reaction products of acetonitrile on Si(111)-7x7 are similar to those detected on the Si(001)-2x1 surface at the same temperature, despite the marked differences in the reconstruction of those two surfaces, especially the distance between adjacent silicon broken bonds. In that respect, we discuss how adatom backbond breaking in the course of adsorption may explain why both surface orientations react the same way with acetonitrile.

Bournel, F.; Carniato, S.; Dufour, G.; Gallet, J.-J.; Ilakovac, V.; Rangan, S.; Rochet, F.; Sirotti, F. [Laboratoire de Chimie Physique Matiere et Rayonnement, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, Boite Postale 48, 91192 Gif sur Yvette Cedex (France)

2006-03-15T23:59:59.000Z

372

Revisiting density functionals for the primitive model of electric double layers  

SciTech Connect (OSTI)

Density functional theory (DFT) calculations are typically based on approximate functionals that link the free energy of a multi-body system of interest with the underlying one-body density distributions. Whereas good performance is often proclaimed for new developments, it is difficult to vindicate the theoretical merits relative to alternative versions without extensive comparison with the numerical results from molecular simulations. Besides, approximate functionals may defy statistical-mechanical sum rules and result in thermodynamic inconsistency. Here we compare systematically several versions of density functionals for ionic distributions near a charged surface using the primitive model of electric double layers. We find that the theoretical performance is sensitive not only to the specific forms of the density functional but also to the range of parameter space and the precise properties under consideration. In general, incorporation of the thermodynamic sum rule into the DFT calculations shows significant improvements for both electrochemical properties and ionic distributions.

Jiang, Jian [Department of Chemical and Environmental Engineering and Department of Mathematics, University of California, Riverside, California 92521 (United States) [Department of Chemical and Environmental Engineering and Department of Mathematics, University of California, Riverside, California 92521 (United States); Department of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Cao, Dapeng, E-mail: jwu@engr.ucr.edu, E-mail: doug@chem.byu.edu, E-mail: caodp@mail.buct.edu.cn [Department of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)] [Department of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Henderson, Douglas, E-mail: jwu@engr.ucr.edu, E-mail: doug@chem.byu.edu, E-mail: caodp@mail.buct.edu.cn [Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602 (United States)] [Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602 (United States); Wu, Jianzhong, E-mail: jwu@engr.ucr.edu, E-mail: doug@chem.byu.edu, E-mail: caodp@mail.buct.edu.cn [Department of Chemical and Environmental Engineering and Department of Mathematics, University of California, Riverside, California 92521 (United States)] [Department of Chemical and Environmental Engineering and Department of Mathematics, University of California, Riverside, California 92521 (United States)

2014-01-28T23:59:59.000Z

373

Implementation and benchmark of a long-range corrected functional in the density functional based tight-binding method  

E-Print Network [OSTI]

Bridging the gap between first principles methods and empirical schemes, the density functional based tight-binding method (DFTB) has become a versatile tool in predictive atomistic simulations over the past years. One of the major restrictions of this method is the limitation to local or gradient corrected exchange-correlation functionals. This excludes the important class of hybrid or long-range corrected functionals, which are advantageous in thermochemistry, as well as in the computation of vibrational, photoelectron and optical spectra. The present work provides a detailed account of the implementation of DFTB for a long-range corrected functional in generalized Kohn-Sham theory. We apply the method to a set of organic molecules and compare ionization potentials and electron affinities with the original DFTB method and higher level theory. The new scheme cures the significant overpolarization in electric fields found for local DFTB, which parallels the functional dependence in first principles density fu...

Lutsker, Vitalij; Niehaus, Thomas A

2015-01-01T23:59:59.000Z

374

The Performance of Density Functionals for Sulfate-Water Clusters  

SciTech Connect (OSTI)

The performance of 24 density functionals, Hartree-Fock, and MP2 is assessed with respect to the energetics of 49 sulfate-water clusters with between three and six water molecules. Included among the density functionals are GGA, meta-GGA, hybrid GGA, hybrid meta-GGA, and double hybrid density functionals, as well as the LDA. Three types of dispersion corrections (VV10, XDM, and -D) are tested in conjunction with these functionals. The functionals are compared using the relative and binding energies of the sulfatewater clusters as the main criteria. It is discovered that a majority of current density functionals are unable to simultaneously capture the physics necessary to describe both the relative and binding energies of the anionic solvation clusters. The only density functionals that perform acceptably with respect to both measures are XYG3 and XYGJOS, primarily due to their balanced treatment of exchange and correlation. On the other hand, density functionals with exact exchange that lack nonlocal correlation tend to perform well only for the relative energies. However, there is evidence that hybrid density functionals that provide a more comprehensive treatment of local correlation through their dependence on the kinetic energy density and their ability to treat the inhomogeneities in the present system can partially resolve this issue. While dispersion correction functionals cannot replace the accuracy provided by MP2 correlation, it is shown that the proper combination of a hybrid GGA functional with a dispersion correction functional can lead to drastic improvements in the binding energies of the parent functional, while preserving its performance with respect to the relative energies.

Mardirossian, Narbe; Lambrecht, Daniel S.; McCaslin, Laura; Xantheas, Sotiris S.; Head-Gordon, Martin P.

2013-03-12T23:59:59.000Z

375

Density-matrix functionals for pairing in mesoscopic superconductors  

E-Print Network [OSTI]

A functional theory based on single-particle occupation numbers is developed for pairing. This functional, that generalizes the BCS approach, directly incorporates corrections due to particle number conservation. The functional is benchmarked with the pairing Hamiltonian and reproduces perfectly the energy for any particle number and coupling.

Denis Lacroix; Guillaume Hupin

2010-09-03T23:59:59.000Z

376

Calculations of free energies in liquid and solid phases: Fundamental measure density-functional approach  

E-Print Network [OSTI]

Calculations of free energies in liquid and solid phases: Fundamental measure density, a theoretical description of the free energies and correlation functions of hard-sphere (HS) liquid and solid-Chandler-Andersen perturbation theory, free energies of liquid and solid phases with many interaction potentials can be obtained

Song, Xueyu

377

A density functional study of actinyl containing complexes.  

E-Print Network [OSTI]

??Density functional (DFT) methods are first used to study 22 of the most stable solution-phase UN4O12 isomers containing uranyl nitrate, UO2(NO3)2. Based on relative free (more)

Berard, Joel J.

2008-01-01T23:59:59.000Z

378

Linear response of homogeneous nuclear matter with energy density functionals  

E-Print Network [OSTI]

Response functions of infinite nuclear matter with arbitrary isospin asymmetry are studied in the framework of the random phase approximation. The residual interaction is derived from a general nuclear Skyrme energy density functional. Besides the usual central, spin-orbit and tensor terms it could also include other components as new density-dependent terms or three-body terms. Algebraic expressions for the response functions are obtained from the Bethe-Salpeter equation for the particle-hole propagator. Applications to symmetric nuclear matter, pure neutron matter and asymmetric nuclear matter are presented and discussed. Spin-isospin strength functions are analyzed for varying conditions of density, momentum transfer, isospin asymmetry, and temperature for some representative Skyrme functionals. Particular attention is paid to the discussion of instabilities, either real or unphysical, which could manifest in finite nuclei.

A. Pastore; D. Davesne; J. Navarro

2014-12-07T23:59:59.000Z

379

Ensemble density variational methods with self- and ghost-interaction-corrected functionals  

SciTech Connect (OSTI)

Ensemble density functional theory (DFT) offers a way of predicting excited-states energies of atomic and molecular systems without referring to a density response function. Despite a significant theoretical work, practical applications of the proposed approximations have been scarce and they do not allow for a fair judgement of the potential usefulness of ensemble DFT with available functionals. In the paper, we investigate two forms of ensemble density functionals formulated within ensemble DFT framework: the Gross, Oliveira, and Kohn (GOK) functional proposed by Gross et al. [Phys. Rev. A 37, 2809 (1988)] alongside the orbital-dependent eDFT form of the functional introduced by Nagy [J. Phys. B 34, 2363 (2001)] (the acronym eDFT proposed in analogy to eHF ensemble Hartree-Fock method). Local and semi-local ground-state density functionals are employed in both approaches. Approximate ensemble density functionals contain not only spurious self-interaction but also the so-called ghost-interaction which has no counterpart in the ground-state DFT. We propose how to correct the GOK functional for both kinds of interactions in approximations that go beyond the exact-exchange functional. Numerical applications lead to a conclusion that functionals free of the ghost-interaction by construction, i.e., eDFT, yield much more reliable results than approximate self- and ghost-interaction-corrected GOK functional. Additionally, local density functional corrected for self-interaction employed in the eDFT framework yields excitations energies of the accuracy comparable to that of the uncorrected semi-local eDFT functional.

Pastorczak, Ewa [Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, ul. Wroblewskiego 15, 93-590 Lodz (Poland)] [Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, ul. Wroblewskiego 15, 93-590 Lodz (Poland); Pernal, Katarzyna, E-mail: pernalk@gmail.com [Institute of Physics, Lodz University of Technology, ul. Wolczanska 219, 90-924 Lodz (Poland)] [Institute of Physics, Lodz University of Technology, ul. Wolczanska 219, 90-924 Lodz (Poland)

2014-05-14T23:59:59.000Z

380

Quasi-local-density approximation for a van der Waals energy functional  

E-Print Network [OSTI]

We discuss a possible form for a theory akin to local density functional theory, but able to produce van der Waals energies in a natural fashion. The usual Local Density Approximation (LDA) for the exchange and correlation energy $E_{xc}$ of an inhomogeneous electronic system can be derived by making a quasilocal approximation for the {\\it interacting} density-density response function $\\chi (\\vec{r},\\vec{r} ^{\\prime},\\omega)$, then using the fluctuation-dissipation theorem and a Feynman coupling-constant integration to generate $E_{xc}$. The first new idea proposed here is to use the same approach except that one makes a quasilocal approximation for the {\\it bare} response $\\chi ^{0}$, rather than for $\\chi $. The interacting response is then obtained by solving a nonlocal screening integral equation in real space. If the nonlocal screening is done at the time-dependent Hartree level, then the resulting energy is an approximation to the full inhomogeneous RPA energy: we show here that the inhomogeneous RPA correlation energy contains a van der Waals term for the case of widely-separated neutral subsystems. The second new idea is to use a particularly simple way of introducing LDA-like local field corrrections into the screening equations, giving a theory which should remain reasonable for all separations of a pair of subsystems, encompassing both the van der Waals limit much as in RPA and the bonding limit much as in LDA theory.

John F. Dobson

2003-11-17T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
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381

Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies  

E-Print Network [OSTI]

We study a particular class of relativistic nuclear energy density functionals in which only nucleon degrees of freedom are explicitly used in the construction of effective interaction terms. Short-distance (high-momentum) correlations, as well as intermediate and long-range dynamics, are encoded in the medium (nucleon density) dependence of the strength functionals of an effective interaction Lagrangian. Guided by the density dependence of microscopic nucleon self-energies in nuclear matter, a phenomenological ansatz for the density-dependent coupling functionals is accurately determined in self-consistent mean-field calculations of binding energies of a large set of axially deformed nuclei. The relationship between the nuclear matter volume, surface and symmetry energies, and the corresponding predictions for nuclear masses is analyzed in detail. The resulting best-fit parametrization of the nuclear energy density functional is further tested in calculations of properties of spherical and deformed medium-heavy and heavy nuclei, including binding energies, charge radii, deformation parameters, neutron skin thickness, and excitation energies of giant multipole resonances.

T. Niksic; D. Vretenar; P. Ring

2008-09-08T23:59:59.000Z

382

Time-dependent potential-functional embedding theory  

SciTech Connect (OSTI)

We introduce a time-dependent potential-functional embedding theory (TD-PFET), in which atoms are grouped into subsystems. In TD-PFET, subsystems can be propagated by different suitable time-dependent quantum mechanical methods and their interactions can be treated in a seamless, first-principles manner. TD-PFET is formulated based on the time-dependent quantum mechanics variational principle. The action of the total quantum system is written as a functional of the time-dependent embedding potential, i.e., a potential-functional formulation. By exploiting the Runge-Gross theorem, we prove the uniqueness of the time-dependent embedding potential under the constraint that all subsystems share a common embedding potential. We derive the integral equation that such an embedding potential needs to satisfy. As proof-of-principle, we demonstrate TD-PFET for a Na{sub 4} cluster, in which each Na atom is treated as one subsystem and propagated by time-dependent Kohn-Sham density functional theory (TDDFT) using the adiabatic local density approximation (ALDA). Our results agree well with a direct TDDFT calculation on the whole Na{sub 4} cluster using ALDA. We envision that TD-PFET will ultimately be useful for studying ultrafast quantum dynamics in condensed matter, where key regions are solved by highly accurate time-dependent quantum mechanics methods, and unimportant regions are solved by faster, less accurate methods.

Huang, Chen, E-mail: chenh@lanl.gov [Theoretical Division, Los Alamos National Laboratory, New Mexico 87544 (United States)] [Theoretical Division, Los Alamos National Laboratory, New Mexico 87544 (United States); Libisch, Florian [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrae 8-10/136, 1040 Vienna (Austria)] [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrae 8-10/136, 1040 Vienna (Austria); Peng, Qing [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)] [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Carter, Emily A., E-mail: eac@princeton.edu [Department of Mechanical and Aerospace Engineering and Chemistry, Program in Applied and Computational Mathematics, and Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544 (United States)

2014-03-28T23:59:59.000Z

383

Density functional and theoretical study of the temperature and pressure dependency of the plasmon energy of solids  

SciTech Connect (OSTI)

The temperature and pressure dependency of the volume plasmon energy of solids was investigated by density functional theory calculations. The volume change of crystal is the major factor responsible for the variation of valence electron density and plasmon energy in the free electron model. Hence, to introduce the effect of temperature and pressure for the density functional theory calculations of plasmon energy, the temperature and pressure dependency of lattice parameter was used. Also, by combination of the free electron model and the equation of state based on the pseudo-spinodal approach, the temperature and pressure dependency of the plasmon energy was modeled. The suggested model is in good agreement with the results of density functional theory calculations and available experimental data for elements with the free electron behavior.

Attarian Shandiz, M., E-mail: mohammad.attarianshandiz@mail.mcgill.ca; Gauvin, R. [Department of Materials Engineering, McGill University, Montreal, Quebec H3A 0C5 (Canada)

2014-10-28T23:59:59.000Z

384

Density matrix renormalization group and wave function factorization for nuclei  

E-Print Network [OSTI]

We employ the density matrix renormalization group (DMRG) and the wave function factorization method for the numerical solution of large scale nuclear structure problems. The DMRG exhibits an improved convergence for problems with realistic interactions due to the implementation of the finite algorithm. The wave function factorization of fpg-shell nuclei yields rapidly converging approximations that are at the present frontier for large-scale shell model calculations.

T. Papenbrock; D. J. Dean

2005-07-15T23:59:59.000Z

385

The intrapair electron correlation in natural orbital functional theory  

SciTech Connect (OSTI)

A previously proposed [M. Piris, X. Lopez, F. Ruiprez, J. M. Matxain, and J. M. Ugalde, J. Chem. Phys. 134, 164102 (2011)] formulation of the two-particle cumulant, based on an orbital-pairing scheme, is extended here for including more than two natural orbitals. This new approximation is used to reconstruct the two-particle reduced density matrix (2-RDM) constrained to the D, Q, and G positivity necessary conditions of the N-representable 2-RDM. In this way, we have derived an extended version of the Piris natural orbital functional 5 (PNOF5e). An antisymmetrized product of strongly orthogonal geminals with the expansion coefficients explicitly expressed by the occupation numbers is also used to generate the PNOF5e. The theory is applied to the homolytic dissociation of selected diatomic molecules: H{sub 2}, LiH, and Li{sub 2}. The Bader's theory of atoms in molecules is used to analyze the electron density and the presence of non-nuclear maxima in the case of a set of light atomic clusters: Li{sub 2}, Li {sub 3}{sup +}, Li {sub 4}{sup 2+}, and H{sub 3}{sup +}. The improvement of PNOF5e over PNOF5 was observed by visualizing the electron densities.

Piris, M. [Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia (Spain) [Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia (Spain); Donostia International Physics Center (DIPC), 20018 Donostia (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain); Matxain, J. M.; Lopez, X. [Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia (Spain) [Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia (Spain); Donostia International Physics Center (DIPC), 20018 Donostia (Spain)

2013-12-21T23:59:59.000Z

386

Finite-size instabilities in nuclear energy density functionals  

SciTech Connect (OSTI)

The systematic lack of convergence of self-consistent mean-field calculations with certain parameterizations of the Skyrme energy density functional has been attributed to the appearance of finite-size instabilities. In this contribution, we investigate what happens at the instability associated with the C{sub 0}{sup {Delta}s}s{sub 0} Dot-Operator {Delta}s{sub 0} term in a high-spin state of the superdeformed band in {sup 194}Hg.

Hellemans, V.; Heenen, P.-H.; Bender, M. [Universite Libre de Bruxelles, PNTPM, CP229, 1050 Bruxelles (Belgium); Univ. Bordeaux, CENBG, UMR5797, F-33170 Gradignan (France) and CNRS/IN2P3, CENBG, UMR5797, F-33170 Gradignan (France)

2012-10-20T23:59:59.000Z

387

Measuring the Density Fluctuation From the Cluster Gas Mass Function  

E-Print Network [OSTI]

We investigate the gas mass function of clusters of galaxies to measure the density fluctuation spectrum on cluster scales. The baryon abundance confined in rich clusters is computed from the gas mass function and compared with the mean baryon density in the universe which is predicted by the Big Bang Nucleosynthesis. This baryon fraction and the slope of the gas mass function put constraints on $\\sigma_8$, the rms linear fluctuation on scales of $8h^{-1}\\Mpc$, and the slope of the fluctuation spectrum, where $h$ is the Hubble constant in units of 100 $\\kms \\oMpc$. We find $\\sigma_8 = 0.80 \\pm 0.15$ and $n \\sim -1.5$ for $0.5 \\le h \\le 0.8$, where we assume that the density spectrum is approximated by a power law on cluster scales: $\\sigma(r) \\propto r^{-{3+n\\over{2}}}$. Our value of $\\sigma_8$ is independent of the density parameter, $\\Omega_0$, and thus we can estimate $\\Omega_0$ by combining $\\sigma_8$ obtained in this study with those from $\\Omega_0$-dependent analyses to date. We find that $\\sigma_8(\\Omega_0)$ derived from the cluster abundance such as the temperature function gives $\\Omega_0 \\sim 0.5$ while $\\sigma_8(\\Omega_0)$ measured from the peculiar velocity field of galaxies gives $\\Omega_0 \\sim 0.2-1$, depending on the technique used to analyze peculiar velocity data. Constraints are also derived for open, spatially flat, and tilted Cold Dark Matter models and for Cold + Hot Dark Matter models.

Kazuhiro Shimasaku

1997-01-27T23:59:59.000Z

388

Using Fundamental Measure Theory to Treat the Correlation Function of the Inhomogeneous Hard-Sphere Fluid  

E-Print Network [OSTI]

We investigate the value of the correlation function of an inhomogeneous hard-sphere fluid at contact. This quantity plays a critical role in Statistical Associating Fluid Theory (SAFT), which is the basis of a number of recently developed classical density functionals. We define two averaged values for the correlation function at contact, and derive formulas for each of them from the White Bear version of the Fundamental Measure Theory functional, using an assumption of thermodynamic consistency. We test these formulas, as well as two existing formulas against Monte Carlo simulations, and find excellent agreement between the Monte Carlo data and one of our averaged correlation functions.

Jeff Schulte; Patrick Kreitzberg; Chris Haglund; David Roundy

2012-08-31T23:59:59.000Z

389

Fundamental gaps with approximate density functionals: The derivative discontinuity revealed from ensemble considerations  

SciTech Connect (OSTI)

The fundamental gap is a central quantity in the electronic structure of matter. Unfortunately, the fundamental gap is not generally equal to the Kohn-Sham gap of density functional theory (DFT), even in principle. The two gaps differ precisely by the derivative discontinuity, namely, an abrupt change in slope of the exchange-correlation energy as a function of electron number, expected across an integer-electron point. Popular approximate functionals are thought to be devoid of a derivative discontinuity, strongly compromising their performance for prediction of spectroscopic properties. Here we show that, in fact, all exchange-correlation functionals possess a derivative discontinuity, which arises naturally from the application of ensemble considerations within DFT, without any empiricism. This derivative discontinuity can be expressed in closed form using only quantities obtained in the course of a standard DFT calculation of the neutral system. For small, finite systems, addition of this derivative discontinuity indeed results in a greatly improved prediction for the fundamental gap, even when based on the most simple approximate exchange-correlation density functional the local density approximation (LDA). For solids, the same scheme is exact in principle, but when applied to LDA it results in a vanishing derivative discontinuity correction. This failure is shown to be directly related to the failure of LDA in predicting fundamental gaps from total energy differences in extended systems.

Kraisler, Eli; Kronik, Leeor [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel)] [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel)

2014-05-14T23:59:59.000Z

390

Building a Universal Nuclear Energy Density Functional (UNEDF): SciDAC-2 Project  

SciTech Connect (OSTI)

An understanding of the properties of atomic nuclei is crucial for a complete nuclear theory, for element formation, for properties of stars, and for present and future energy and defense applications. During the period of Dec. 1, 2006 - Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. The long-term vision initiated with UNEDF is to arrive at a comprehensive, quantitative, and unified description of nuclei and their reactions, grounded in the fundamental interactions between the constituent nucleons. We seek to replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that delivers maximum predictive power with well-quantified uncertainties. Specifically, the mission of this project has been three-fold: first, to find an optimal energy density functional (EDF) using all our knowledge of the nucleonic Hamiltonian and basic nuclear properties; second, to apply the EDF theory and its extensions to validate the functional using all the available relevant nuclear structure and reaction data; and third, to apply the validated theory to properties of interest that cannot be measured, in particular the properties needed for reaction theory.

Carlson, Joe; Furnstahl, Dick; Lusk, Rusty; Nazarewicz, Witek; Ng, Esmond; Thompson, Ian; Vary, James

2012-06-30T23:59:59.000Z

391

Towards the island of stability with relativistic energy density functionals  

SciTech Connect (OSTI)

Relativistic energy density functionals (REDF) provide a complete and accurate, global description of nuclear structure phenomena. Modern semi-empirical functionals, adjusted to the nuclear matter equation of state and to empirical masses of deformed nuclei, are applied to studies of shapes of superheavy nuclei. The theoretical framework is tested in a comparison to empirical masses, quadrupole deformations, and energy barriers of actinide nuclei. The model is used in a self-consistent mean-field calculation of spherical, axial and triaxial shapes of superheavy nuclei, alpha-decay energies and lifetimes. The effect of explicit treatment of collective correlations is analyzed in calculations that consistently use a collective Hamiltonian model based on REDFs.

Prassa, V.; Niksic, T.; Lalazissis, G. A.; Vretenar, D. [Physics Department, University of Jyvaeskylae, P.O. Box 35 (YFL) FI-40014, Finland and Department of Theoretical Physics, Aristotle University Thessaloniki, GR-54124 (Finland); Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Department of Theoretical Physics, Aristotle University Thessaloniki, GR-54124 (Greece); Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia)

2012-10-20T23:59:59.000Z

392

Power-law tails in probability density functions of molecular cloud column density  

E-Print Network [OSTI]

Power-law tails are often seen in probability density functions (PDFs) of molecular cloud column densities, and have been attributed to the effect of gravity. We show that extinction PDFs of a sample of five molecular clouds obtained at a few tenths of a parsec resolution, probing extinctions up to A$_{{\\mathrm{V}}}$ $\\sim$ 10 magnitudes, are very well described by lognormal functions provided that the field selection is tightly constrained to the cold, molecular zone and that noise and foreground contamination are appropriately accounted for. In general, field selections that incorporate warm, diffuse material in addition to the cold, molecular material will display apparent core+tail PDFs. The apparent tail, however, is best understood as the high extinction part of a lognormal PDF arising from the cold, molecular part of the cloud. We also describe the effects of noise and foreground/background contamination on the PDF structure, and show that these can, if not appropriately accounted for, induce spurious ...

Brunt, Chris

2015-01-01T23:59:59.000Z

393

Self-interaction-free time-dependent density-functional theory for molecular processes in strong fields:? High-order harmonic generation of H2 in intense laser fields  

E-Print Network [OSTI]

.29 215.30 25 210.20 210.19 49 216.48 216.50 FIG. 2. The induced dipole moment ^ z(t) & and dipole accelera- tion ^ (d2z(t)/dt2)/v02& of H2 at R51.4a0 as a function of time ~in optical cycles!. The laser intensity is 1014 W/cm2 and wavelength 1064 nm...

Chu, Shih-I; Chu, Xi

2001-01-17T23:59:59.000Z

394

Density Functional Studies on the Complexation and Spectroscopy of Uranyl Ligated with Acetonitrile and Acetone Derivatives  

SciTech Connect (OSTI)

The coordination of nitrile (acetonitrile, propionitrile, and benzonitrile) and carbonyl (formaldehyde, ethanal, and acetone) ligands to the uranyl dication (UO22+) has been examined using density functional theory (DFT) utilizing relativistic effective core potentials (RECPs). Complexes containing up to six ligands have been modeled for all ligands except formaldehyde, for which no minimum could be found. A comparison of relative binding energies indicates that five coordinate complexes are predominant while a six coordinate complex involving propionitrile ligands might be possible. Additionally, the relative binding energy and the weakening of the uranyl bond is related to the size of the ligand and, in general, nitriles bind more strongly to uranyl than carbonyls.

Schoendorff, George E.; Windus, Theresa L.; De Jong, Wibe A.

2009-12-12T23:59:59.000Z

395

Cosmic density and velocity fields in Lagrangian perturbation theory  

E-Print Network [OSTI]

A first- and second-order relation between cosmic density and peculiar-velocity fields is presented. The calculation is purely Lagrangian and it is derived using the second-order solutions of the Lagrange-Newton system obtained by Buchert & Ehlers. The procedure is applied to two particular solutions given generic initial conditions. In this approach, the continuity equation yields a relation between the over-density and peculiar-velocity fields that automatically satisfies Euler's equation because the orbits are derived from the Lagrange-Newton system. This scheme generalizes some results obtained by Nusser et al. (1991) in the context of the Zel'dovich approximation. As opposed to several other reconstruction schemes, in this approach it is not necessary to truncate the expansion of the Jacobian given by the continuity equation in order to calculate a first- or second-order expression for the density field. In these previous schemes, the density contrast given by (a) the continuity equation and (b) Euler's equation are mutually incompatible. This inconsistency arises as a consequence of an improper handling of Lagrangian and Eulerian coordinates in the analysis. Here, we take into account the fact that an exact calculation of the density is feasible in the Lagrangian picture and therefore an accurate and consistent description is obtained.

Mikel Susperregi; Thomas Buchert

1997-08-04T23:59:59.000Z

396

Self-interaction corrected density functional calculations of molecular Rydberg states  

SciTech Connect (OSTI)

A method is presented for calculating the wave function and energy of Rydberg excited states of molecules. A good estimate of the Rydberg state orbital is obtained using ground state density functional theory including Perdew-Zunger self-interaction correction and an optimized effective potential. The total energy of the excited molecule is obtained using the Delta Self-Consistent Field method where an electron is removed from the highest occupied orbital and placed in the Rydberg orbital. Results are presented for the first few Rydberg states of NH{sub 3}, H{sub 2}O, H{sub 2}CO, C{sub 2}H{sub 4}, and N(CH{sub 3}){sub 3}. The mean absolute error in the energy of the 33 molecular Rydberg states presented here is 0.18 eV. The orbitals are represented on a real space grid, avoiding the dependence on diffuse atomic basis sets. As in standard density functional theory calculations, the computational effort scales as NM{sup 2} where N is the number of orbitals and M is the number of grid points included in the calculation. Due to the slow scaling of the computational effort with system size and the high level of parallelism in the real space grid approach, the method presented here makes it possible to estimate Rydberg electron binding energy in large molecules.

Gudmundsdttir, Hildur [Science Institute of the University of Iceland, 107 Reykjavk (Iceland)] [Science Institute of the University of Iceland, 107 Reykjavk (Iceland); Zhang, Yao; Weber, Peter M. [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)] [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States); Jnsson, Hannes [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States) [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States); Faculty of Physical Sciences, VR-III, University of Iceland, 107 Reykjavk (Iceland)

2013-11-21T23:59:59.000Z

397

Dipole polarizability of 120Sn and nuclear energy density functionals  

E-Print Network [OSTI]

The electric dipole strength distribution in 120Sn between 5 and 22 MeV has been determined at RCNP Osaka from a polarization transfer analysis of proton inelastic scattering at E_0 = 295 MeV and forward angles including 0{\\deg}. Combined with photoabsorption data an electric dipole polarizability alpha_D(120Sn) = 8.93(36) fm^3 is extracted. The correlation of this value with alpha_D for 208Pb serves as a test of energy density functionals (EDFs). The majority of models based on Skyrme interactions can describe the data while relativistic approaches fail. The accuracy of the experimental results provides important constraints on the static isovector properties of EDFs used to predict symmetry energy parameters and the neutron skin thickness of nuclei.

Hashimoto, T; Reinhard, P -G; Tamii, A; von Neumann-Cosel, P; Adachi, T; Aoi, N; Bertulani, C A; Fujita, H; Fujita, Y; Ganio?lu, E; Hatanaka, K; Iwamoto, C; Kawabata, T; Khai, N T; Krugmann, A; Martin, D; Matsubara, H; Miki, K; Neveling, R; Okamura, H; Ong, H J; Poltoratska, I; Ponomarev, V Yu; Richter, A; Sakaguchi, H; Shimbara, Y; Shimizu, Y; Simonis, J; Smit, F D; Ssoy, G; Thies, J H; Suzuki, T; Yosoi, M; Zenihiro, J

2015-01-01T23:59:59.000Z

398

Interactions in 1-ethyl-3-methyl imidazolium tetracyanoborate ion pair: Spectroscopic and density functional study  

SciTech Connect (OSTI)

Density Functional Theory is used to investigate a weakly coordinating room-temperature ionic liquid, 1-ethyl-3-methyl imidazolium tetracyanoborate ([Emim]{sup +}[TCB]{sup -}). Four locally stable conformers of the ion pair were located. Atoms-in-molecules (AIM) and electron density analysis indicated the existence of several hydrogen bonds. Further investigation through the Natural Bond Orbital (NBO) and Natural Energy Decomposition Analysis (NEDA) calculations provided insight into the origin of interactions in the [Emim]{sup +}[TCB]{sup -} ion pair. Strength of molecular interactions in the ionic liquid was correlated with frequency shifts of the characteristic vibrations of the ion pair. Harmonic vibrations of the ion pair were also compared with the experimental Raman and Infrared spectra. Vibrational frequencies were assigned by visualizing displacements of atoms around their equilibrium positions and through Potential Energy Distribution (PED) analysis.

Mao, James X.; Lee, Anita S.; Kitchin, John R.; Nulwala, Hunaid B; Luebke, David R.; Damodaran, Krishnan

2013-04-24T23:59:59.000Z

399

Ground state properties and high pressure behavior of plutonium dioxide: Systematic density functional calculations  

E-Print Network [OSTI]

Plutonium dioxide is of high technological importance in nuclear fuel cycle and is particularly crucial in long-term storage of Pu-based radioactive waste. Using first-principles density-functional theory, in this paper we systematically study the structural, electronic, mechanical, thermodynamic properties, and pressure induced structural transition of PuO$_{2}$. To properly describe the strong correlation in the Pu $5f$ electrons, the local density approximation$+U$ and the generalized gradient approximation$+U$ theoretical formalisms have been employed. We optimize the $U$ parameter in calculating the total energy, lattice parameters, and bulk modulus at the nonmagnetic, ferromagnetic, and antiferromagnetic configurations for both ground state fluorite structure and high pressure cotunnite structure. The best agreement with experiments is obtained by tuning the effective Hubbard parameter $U$ at around 4 eV within the LDA$+U$ approach. After carefully testing the validity of the ground state, we further in...

Zhang, Ping; Zhao, Xian-Geng

2010-01-01T23:59:59.000Z

400

DENSITY-FUNCTIONAL STUDY OF U-Mo AND U-Zr ALLOYS  

SciTech Connect (OSTI)

Density-functional theory previously used to describe phase equilibria in U-Zr alloys [A. Landa, P. Soederlind, P.E.A. Turchi, J. Alloys Comp. 478 (2009) 103-110] is extended to investigate the ground-state properties of U-Mo solid solutions. We discuss how the heat of formation in both alloys correlates with the charge transfer between the alloy components, and how the specific behavior of the density of states in the vicinity of the Fermi level promotes the stabilization of the U{sub 2}Mo compound. Our calculations prove that, due to the existence of a single {gamma}-phase over the typical fuel operation temperatures, {gamma}-U-Mo alloys should indeed have much lower constituent redistribution than {gamma}-U-Zr alloys for which binodal decomposition causes a high degree of constituent redistribution.

Landa, A; Soderlind, P; Turchi, P A

2010-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Statistical mechanical theory for steady state systems. V. Nonequilibrium probability density  

E-Print Network [OSTI]

Statistical mechanical theory for steady state systems. V. Nonequilibrium probability density Phil is shown to be much more efficient for the thermal conductivity of a Lennard-Jones fluid than the Green probability densities for hydrodynamic transport, for time-dependent mechanical work, and for nonequilibrium

Attard, Phil

402

Density of the Values Set of the Tau Function  

E-Print Network [OSTI]

It is shown that the density of the values set {Tau(n): n > x/log x. The currently known density is #{Tau(n) : n > x^(1/2+o(1)), and the expected density is #{Tau(n) : n 2, which arises as a singular case of this analysis, is discussed within.

N. A. Carella

2014-04-10T23:59:59.000Z

403

Mass Spectrometry and Density Functional Theory Characterizations of DNA Modifications  

E-Print Network [OSTI]

alkaline phosphatase (CIP). We chose Incorporation of DNADigestion NP1, exoPII, CIP, exoPI + Internal Standard Enzymethe addition of exoPI and CIP. Similar to NPI, exoPI creates

Williams, Renee Therese

2012-01-01T23:59:59.000Z

404

Time-dependent density functional theory for ion diffusion in...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

The cell width, L, is defined by the distance accessible to the ion centers. (B) An equivalent circuit model for the electrochemical cell. system considered above, the EC...

405

Density Functional Theory Studies of the Electronic Structure of Solid  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData Files DataADVANCES IN TIME-RESOLVED

406

Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData Files DataADVANCES IN TIME-RESOLVEDPlatinum Nanotubes. |

407

A Density Functional Theory Study of Formaldehyde Adsorption on Ceria. |  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert SouthwestTechnologies |November 2011 Mon,Electrocatalysis |FrameworkPredictiveDFT

408

The Materials Project: Combining Density Functional Theory Calculations  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassiveSubmittedStatus TomAboutManusScienceThe Life of Enrico Fermi The Thewithwith

409

A Combined Density Functional Theory and Monte Carlo Study of...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

to the first order nature. Despite many experimental efforts to enhance the isothermal entropy change in manganites, the maximum obtained value merely reaches a modest value in...

410

Enhanced von Weizscker Wang-Govind-Carter kinetic energy density functional for semiconductors  

SciTech Connect (OSTI)

We propose a new form of orbital-free (OF) kinetic energy density functional (KEDF) for semiconductors that is based on the Wang-Govind-Carter (WGC99) nonlocal KEDF. We enhance within the latter the semi-local von Weizscker KEDF term, which is exact for a single orbital. The enhancement factor we introduce is related to the extent to which the electron density is localized. The accuracy of the new KEDF is benchmarked against Kohn-Sham density functional theory (KSDFT) by comparing predicted energy differences between phases, equilibrium volumes, and bulk moduli for various semiconductors, along with metal-insulator phase transition pressures. We also compare point defect and (100) surface energies in silicon for a broad test of its applicability. This new KEDF accurately reproduces the exact non-interacting kinetic energy of KSDFT with only one additional adjustable parameter beyond the three parameters in the WGC99 KEDF; it exhibits good transferability between semiconducting to metallic silicon phases and between various III-V semiconductors without parameter adjustment. Overall, this KEDF is more accurate than previously proposed OF KEDFs (e.g., the Huang-Carter (HC) KEDF) for semiconductors, while the computational efficiency remains at the level of the WGC99 KEDF (several hundred times faster than the HC KEDF). This accurate, fast, and transferable new KEDF holds considerable promise for large-scale OFDFT simulations of metallic through semiconducting materials.

Shin, Ilgyou [Department of Chemistry, Princeton University, Princeton, New Jersey 08544-1009 (United States)] [Department of Chemistry, Princeton University, Princeton, New Jersey 08544-1009 (United States); Carter, Emily A., E-mail: eac@princeton.edu [Department of Mechanical and Aerospace Engineering, Program in Applied and Computational Mathematics, and Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544-5263 (United States)

2014-05-14T23:59:59.000Z

411

Unification of Field Theory and Maximum Entropy Methods for Learning Probability Densities  

E-Print Network [OSTI]

Bayesian field theory and maximum entropy are two methods for learning smooth probability distributions (a.k.a. probability densities) from finite sampled data. Both methods were inspired by statistical physics, but the relationship between them has remained unclear. Here I show that Bayesian field theory subsumes maximum entropy density estimation. In particular, the most common maximum entropy methods are shown to be limiting cases of Bayesian inference using field theory priors that impose no boundary conditions on candidate densities. This unification provides a natural way to test the validity of the maximum entropy assumption on one's data. It also provides a better-fitting nonparametric density estimate when the maximum entropy assumption is rejected.

Kinney, Justin B

2014-01-01T23:59:59.000Z

412

Density Functional Investigation of Melamine-Formaldehyde Crosslinking Agents Part 1: Partially Substituted Melamine  

SciTech Connect (OSTI)

Computational modeling has been performed on the cross-linking mechanism of partially substituted melamine reacting with poly(vinyl alcohol). Ab initio calculations were performed with density functional theory employing the BLYP functional and double numerical DND basis set. The mechanism, general acid catalysis, has been modeled with respect to structures, protonation, and reaction with a polymer. Protonation of the oxygen is required initially, followed by liberation of methanol. The reaction can take one of two pathways after methanol liberation. The conjugate base of the weak acid can abstract a proton, generating a Schiff-base intermediate. The O-H on the polymer then adds to the C-N double bond, producing the polymer-melamine bond. The alternative is that the polymer adds to the charged melamine, using the specific acid catalysis mechanism. After polymer addition, the proton is abstracted, producing the product.

Benson, Michael Timothy

2003-07-01T23:59:59.000Z

413

Efficiency issues related to probability density function comparison  

SciTech Connect (OSTI)

The CANDID project (Comparison Algorithm for Navigating Digital Image Databases) employs probability density functions (PDFs) of localized feature information to represent the content of an image for search and retrieval purposes. A similarity measure between PDFs is used to identify database images that are similar to a user-provided query image. Unfortunately, signature comparison involving PDFs is a very time-consuming operation. In this paper, we look into some efficiency considerations when working with PDFS. Since PDFs can take on many forms, we look into tradeoffs between accurate representation and efficiency of manipulation for several data sets. In particular, we typically represent each PDF as a Gaussian mixture (e.g. as a weighted sum of Gaussian kernels) in the feature space. We find that by constraining all Gaussian kernels to have principal axes that are aligned to the natural axes of the feature space, computations involving these PDFs are simplified. We can also constrain the Gaussian kernels to be hyperspherical rather than hyperellipsoidal, simplifying computations even further, and yielding an order of magnitude speedup in signature comparison. This paper illustrates the tradeoffs encountered when using these constraints.

Kelly, P.M.; Cannon, M.; Barros, J.E.

1996-03-01T23:59:59.000Z

414

Measuring Earth Matter Density and Testing the MSW Theory  

E-Print Network [OSTI]

In this talk I have raised the question of how the future discovery of leptonic CP violation can be made robust even at accepting the rather large current experimental uncertainties in our knowledges of neutrino propagation in matter. To make progress toward answering the difficult question, I listed ways to proceed: (1) Obtain tighter constraints on the MSW theory by testing it by various neutrino experiments. (2) Measure the matter effect in situ, namely within the experiment for discovering CP violation itself. (3) Uncover leptonic CP violation in a matter effect free environment. I also reported a step made toward the above point (2) by taking neutrino factory as a concrete setting; An accurate in situ measurement of the matter effect looks promising.

Minakata, Hisakazu

2007-01-01T23:59:59.000Z

415

Measuring Earth Matter Density and Testing the MSW Theory  

E-Print Network [OSTI]

In this talk I have raised the question of how the future discovery of leptonic CP violation can be made robust even at accepting the rather large current experimental uncertainties in our knowledges of neutrino propagation in matter. To make progress toward answering the difficult question, I listed ways to proceed: (1) Obtain tighter constraints on the MSW theory by testing it by various neutrino experiments. (2) Measure the matter effect in situ, namely within the experiment for discovering CP violation itself. (3) Uncover leptonic CP violation in a matter effect free environment. I also reported a step made toward the above point (2) by taking neutrino factory as a concrete setting; An accurate in situ measurement of the matter effect looks promising.

Hisakazu Minakata

2007-05-07T23:59:59.000Z

416

Tests of second-generation and third-generation density functionals for thermochemical kineticsy  

E-Print Network [OSTI]

Tests of second-generation and third-generation density functionals for thermochemical kineticsy January 2004 We report tests of second- and third-generation density functionals, for pure density of these methods is tested against each other as well as against first- generation methods (BP86, BLYP, PW91, B3PW

Truhlar, Donald G

417

On Painleve Related Functions Arising in Random Matrix Theory  

E-Print Network [OSTI]

In deriving large n probability distribution function of the rightmost eigenvalue from the classical Random Matrix Theory Ensembles, one is faced with que question of ?finding large n asymptotic of certain coupled set of functions. This paper presents some of these functions in a new light.

Leonard N. Choup

2011-01-27T23:59:59.000Z

418

van der Waals density functionals built upon the electron-gas tradition: Facing the challenge of competing interactions  

SciTech Connect (OSTI)

The theoretical description of sparse matter attracts much interest, in particular for those groundstate properties that can be described by density functional theory (DFT). One proposed approach, the van der Waals density functional (vdW-DF) method, rests on strong physical foundations and offers simple yet accurate and robust functionals. A very recent functional within this method called vdW-DF-cx [K. Berland and P. Hyldgaard, Phys. Rev. B, in print] stands out in its attempt to use an exchange energy derived from the same plasmon-based theory from which the nonlocal correlation energy was derived. Encouraged by its good performance for solids, layered materials, and aromatic molecules, we apply it to several systems that are characterized by competing interactions. These include the ferroelectric response in PbTiO3, the adsorption of small molecules within metal-organic frameworks (MOFs), the graphite/diamond phase transition, and the adsorption of an aromaticmolecule on the Ag(111) surface. Our results indicate that vdW-DF-cx is overall well suited to tackle these challenging systems. In addition to being a competitive density functional for sparse matter, the vdW-DF-cx construction presents a more robust general purpose functional that could be applied to a range of materials problems with a variety of competing interactions.

Berland, Kristian [Chalmers University of Technology, Sweden] [Chalmers University of Technology, Sweden; Arter, Calvin A [Wake Forest University, Winston-Salem] [Wake Forest University, Winston-Salem; Cooper, Valentino R [ORNL] [ORNL; Lee, Dr. Kyuho [Lawrence Berkeley National Laboratory (LBNL)] [Lawrence Berkeley National Laboratory (LBNL); Lundqvist, Prof. Bengt I. [Chalmers University of Technology, Sweden] [Chalmers University of Technology, Sweden; Schroder, Prof. Elsebeth [Chalmers University of Technology, Sweden] [Chalmers University of Technology, Sweden; Thonhauser, Prof. Timo [Wake Forest University, Winston-Salem] [Wake Forest University, Winston-Salem; Hyldgaard, Per [Chalmers University of Technology, Sweden] [Chalmers University of Technology, Sweden

2014-01-01T23:59:59.000Z

419

van der Waals density functionals built upon the electron-gas tradition: Facing the challenge of competing interactions  

SciTech Connect (OSTI)

The theoretical description of sparse matter attracts much interest, in particular for those ground-state properties that can be described by density functional theory. One proposed approach, the van der Waals density functional (vdW-DF) method, rests on strong physical foundations and offers simple yet accurate and robust functionals. A very recent functional within this method called vdW-DF-cx [K. Berland and P. Hyldgaard, Phys. Rev. B 89, 035412 (2014)] stands out in its attempt to use an exchange energy derived from the same plasmon-based theory from which the nonlocal correlation energy was derived. Encouraged by its good performance for solids, layered materials, and aromatic molecules, we apply it to several systems that are characterized by competing interactions. These include the ferroelectric response in PbTiO{sub 3}, the adsorption of small molecules within metal-organic frameworks, the graphite/diamond phase transition, and the adsorption of an aromatic-molecule on the Ag(111) surface. Our results indicate that vdW-DF-cx is overall well suited to tackle these challenging systems. In addition to being a competitive density functional for sparse matter, the vdW-DF-cx construction presents a more robust general-purpose functional that could be applied to a range of materials problems with a variety of competing interactions.

Berland, Kristian [Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Gteborg (Sweden) [Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Gteborg (Sweden); Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Arter, Calvin A.; Thonhauser, T. [Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109 (United States)] [Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109 (United States); Cooper, Valentino R. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6114 (United States)] [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6114 (United States); Lee, Kyuho [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Lundqvist, Bengt I. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Gteborg (Sweden)] [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Gteborg (Sweden); Schrder, Elsebeth; Hyldgaard, Per [Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Gteborg (Sweden)] [Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-412 96 Gteborg (Sweden)

2014-05-14T23:59:59.000Z

420

Materials Theory, Modeling and Simulation | ORNL  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Materials Characterization Materials Theory and Simulation Quantum Monte Carlo Density Functional Theory Monte Carlo Ab Initio Molecular Dynamics Chemical and Materials Theory...

Note: This page contains sample records for the topic "density functional theory" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Symmetry Energy as a Function of Density and Mass  

E-Print Network [OSTI]

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a_a^V=(31.5-33.5) MeV for the volume coefficient and a_a^S=(9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L~95 MeV and K_{sym}~25 MeV.

Pawel Danielewicz; Jenny Lee

2007-08-21T23:59:59.000Z

422

Symmetry Energy as a Function of Density and Mass  

SciTech Connect (OSTI)

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a{sub a}{sup V} = (31.5-33.5) MeV for the volume coefficient and a{sub a}{sup S} = (9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L{approx}95 MeV and K{sub sym}{approx}25 MeV.

Danielewicz, Pawel; Lee, Jenny [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

2007-10-26T23:59:59.000Z

423

Symmetry Energy as a Function of Density and Mass  

E-Print Network [OSTI]

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a_a^V=(31.5-33.5) MeV for the volume coefficient and a_a^S=(9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L~95 MeV and K_{sym}~25 MeV.

Danielewicz, Pawel

2007-01-01T23:59:59.000Z

424

Coumarin Dyes for Dye-Sensitized Solar Cells - A Long-Range-Corrected Density Functional Study  

E-Print Network [OSTI]

The excited-state properties in a series of coumarin solar cell dyes are investigated with a long-range-corrected (LC) functional which asymptotically incorporates Hartree-Fock exchange. Using time-dependent density functional theory (TDDFT), we calculate excitation energies, oscillator strengths, and excited-state dipole moments in each of the dyes as a function of the range-separation paramenter, mu. To investigate the acceptable range of mu and assess the quality of the LC-TDDFT formalism, an extensive comparison is made between LC-BLYP excitation energies and approximate coupled cluster singles and doubles (CC2) calculations. When using a properly-optimized value of mu, we find that the LC technique provides a consistent picture of charge-transfer excitations as a function of molecular size. In contrast, we find that the widely-used B3LYP hybrid functional severely overestimates excited-state dipole moments and underestimates vertical excitations energies, especially for larger dye molecules. The results ...

Wong, Bryan M; 10.1063/1.3025924

2010-01-01T23:59:59.000Z

425

Negative energy densities in integrable quantum field theories at one-particle level  

E-Print Network [OSTI]

We study the phenomenon of negative energy densities in quantum field theories with self-interaction. Specifically, we consider a class of integrable models (including the sinh-Gordon model) in which we investigate the expectation value of the energy density in one-particle states. In this situation, we classify the possible form of the stress-energy tensor from first principles. We show that one-particle states with negative energy density generically exist in non-free situations, and we establish lower bounds for the energy density (quantum energy inequalities). Demanding that these inequalities hold reduces the ambiguity in the stress-energy tensor, in some situations fixing it uniquely. Numerical results for the lowest spectral value of the energy density allow us to demonstrate how negative energy densities depend on the coupling constant and on other model parameters.

Bostelmann, Henning

2015-01-01T23:59:59.000Z

426

Negative energy densities in integrable quantum field theories at one-particle level  

E-Print Network [OSTI]

We study the phenomenon of negative energy densities in quantum field theories with self-interaction. Specifically, we consider a class of integrable models (including the sinh-Gordon model) in which we investigate the expectation value of the energy density in one-particle states. In this situation, we classify the possible form of the stress-energy tensor from first principles. We show that one-particle states with negative energy density generically exist in non-free situations, and we establish lower bounds for the energy density (quantum energy inequalities). Demanding that these inequalities hold reduces the ambiguity in the stress-energy tensor, in some situations fixing it uniquely. Numerical results for the lowest spectral value of the energy density allow us to demonstrate how negative energy densities depend on the coupling constant and on other model parameters.

Henning Bostelmann; Daniela Cadamuro

2015-02-05T23:59:59.000Z

427

Test Functions Space in Noncommutative Quantum Field Theory  

E-Print Network [OSTI]

It is proven that the $\\star$-product of field operators implies that the space of test functions in the Wightman approach to noncommutative quantum field theory is one of the Gel'fand-Shilov spaces $S^{\\beta}$ with $\\beta test functions smears the noncommutative Wightman functions, which are in this case generalized distributions, sometimes called hyperfunctions. The existence and determination of the class of the test function spaces in NC QFT is important for any rigorous treatment in the Wightman approach.

M. Chaichian; M. Mnatsakanova; A. Tureanu; Yu. Vernov

2008-07-26T23:59:59.000Z

428

On the breaking and restoration of symmetries within the nuclear energy density functional formalism  

E-Print Network [OSTI]

We review the notion of symmetry breaking and restoration within the frame of nuclear energy density functional methods. We focus on key differences between wave-function- and energy-functional-based methods. In particular, we point to difficulties encountered within the energy functional framework and discuss new potential constraints on the underlying energy density functional that could make the restoration of broken symmetries better formulated within such a formalism. We refer to Ref.~\\cite{duguet10a} for details.

T. Duguet; J. Sadoudi

2010-10-19T23:59:59.000Z

429

Ionic Asymmetry and Solvent Excluded Volume Effects on Spherical Electric Double Layers: A Density Functional Approach  

SciTech Connect (OSTI)

In this article we present a classical density functional theory for electrical double layers of spherical macroions that extends the capabilities of conventional approaches by accounting for electrostatic ion correlations, size asymmetry and excluded volume effects. The approach is based on a recent approximation introduced by Hansen-Goos and Roth for the hard sphere excess free energy of inhomogeneous fluids (J. Chem. Phys. 124, 154506). It accounts for the proper and efficient description of the effects of ionic asymmetry and solvent excluded volume, especially at high ion concentrations and size asymmetry ratios including those observed in experimental studies. Additionally, we utilize a leading functional Taylor expansion approximation of the ion density profiles. In addition, we use the Mean Spherical Approximation for multi-component charged hard sphere fluids to account for the electrostatic ion correlation effects. These approximations are implemented in our theoretical formulation into a suitable decomposition of the excess free energy which plays a key role in capturing the complex interplay between charge correlations and excluded volume effects. We perform Monte Carlo simulations in various scenarios to validate the proposed approach, obtaining a good compromise between accuracy and computational cost. We use the proposed computational approach to study the effects of ion size, ion size asymmetry and solvent excluded volume on the ion profiles, integrated charge, mean electrostatic potential, and ionic coordination number around spherical macroions in various electrolyte mixtures. Our results show that both solvent hard sphere diameter and density play a dominant role in the distribution of ions around spherical macroions, mainly for experimental water molarity and size values where the counterion distribution is characterized by a tight binding to the macroion, similar to that predicted by the Stern model.

Medasani, Bharat; Ovanesyan, Zaven; Thomas, Dennis G.; Sushko, Maria L.; Marucho, Marcelo

2014-05-29T23:59:59.000Z

430

Functional Keldysh theory of spin torques  

E-Print Network [OSTI]

-function-like repulsive interactions using the Hamiltonian H#3;#1;? ?,#1;? #4; =#8; dx #1;? ?#1;x,t#2; ? #6;2#2;22m ? #7;ext2 #8;z + V0#1;x#2; + Va#1;x#2;#8;a#11;#1;? #1;x,t#2; + 1 c J? #1;x,t#2; ? A#1;x,t#2; + U ? ??#1;x,t#2; ? ??#1;x,t#2; ? ?#1;x,t#2; ? ?#1;x,t#2...;#12; , #1;2#2; where for notational convenience we have introduced the spinor #1;? #1;x,t#2; = #5; ? ?#1;x,t#2; ? ?#1;x,t#2; #6; . #1;3#2; In these expressions, the Heisenberg operators ? #1;x , t#2; anni- hilate an electron in the spin state labeled...

Duine, R. A.; Nunez, A. S.; Sinova, Jairo; MacDonald, A. H.

2007-01-01T23:59:59.000Z

431

Theory and applications of Bessel functions  

E-Print Network [OSTI]

and subtracting )( 3~ ()C) j (X), )( g(X) j?(X) + P' j '(X) J ()C) ? )( ~ ()() g "(y) ? X3?(X) T'()C) + 3 C&) J '(~) ? J ()C)3 (X) = o, & [X W [Z Cx& Z Cx3fj = a 'g/ j J?(x) J (x)J To determine the constant C, note that since A is not an in te ger, z. (. I... / O'W 4 x" x g . y*. r: + ~w" s "z* x+i hei x. The functions ker x, kei x, her x, hei x are similarly defined by the equations K. (& X) = gev)C + cAei. X g. C&"x) = ger ~ + ~ helix . 15. Lommel's Integral Form of J~(x). Theorem (15-A) . For p...

Wasson, William Albert

1949-01-01T23:59:59.000Z

432

Probability-density function for energy perturbations of isolated optical pulses  

E-Print Network [OSTI]

Probability-density function for energy perturbations of isolated optical pulses C. J. Mc to determine the probability-density function (PDF) for noise-induced energy perturbations of isolated (solitary) optical pulses in fiber communication systems. The analytical formula is consistent

Lakoba, Taras I.

433

LES/probability density function approach for the simulation of an ethanol spray flame  

E-Print Network [OSTI]

LES/probability density function approach for the simulation of an ethanol spray flame Colin Heye a an experimental pilot-stabilized ethanol spray flame. In this particular flame, droplet evaporation occurs away: Large-eddy simulation; Probability density function; Flamelet/progress variable approach; Ethanol

Raman, Venkat

434

Applications of Skyrme energy-density functional to fusion reactions spanning the fusion barriers  

E-Print Network [OSTI]

The Skyrme energy density functional has been applied to the study of heavy-ion fusion reactions. The barriers for fusion reactions are calculated by the Skyrme energy density functional with proton and neutron density distributions determined by using restricted density variational (RDV) method within the same energy density functional together with semi-classical approach known as the extended semi-classical Thomas-Fermi method. Based on the fusion barrier obtained, we propose a parametrization of the empirical barrier distribution to take into account the multi-dimensional character of real barrier and then apply it to calculate the fusion excitation functions in terms of barrier penetration concept. A large number of measured fusion excitation functions spanning the fusion barriers can be reproduced well. The competition between suppression and enhancement effects on sub-barrier fusion caused by neutron-shell-closure and excess neutron effects is studied.

Min Liu; Ning Wang; Zhuxia Li; Xizhen Wu; Enguang Zhao

2006-01-25T23:59:59.000Z

435

Photon wave functions, wave-packet quantization of light, and coherence theory  

E-Print Network [OSTI]

The monochromatic Dirac and polychromatic Titulaer-Glauber quantized field theories (QFTs) of electromagnetism are derived from a photon-energy wave function in much the same way that one derives QFT for electrons, that is, by quantization of a single-particle wave function. The photon wave function and its equation of motion are established from the Einstein energy-momentum-mass relation, assuming a local energy density. This yields a theory of photon wave mechanics (PWM). The proper Lorentz-invariant single-photon scalar product is found to be non-local in coordinate space, and is shown to correspond to orthogonalization of the Titulaer-Glauber wave-packet modes. The wave functions of PWM and mode functions of QFT are shown to be equivalent, evolving via identical equations of motion, and completely describe photonic states. We generalize PWM to two or more photons, and show how to switch between the PWM and QFT viewpoints. The second-order coherence tensors of classical coherence theory and the two-photon wave functions are shown to propagate equivalently. We give examples of beam-like states, which can be used as photon wave functions in PWM, or modes in QFT. We propose a practical mode converter based on spectral filtering to convert between wave packets and their corresponding biorthogonal dual wave packets.

Brian J. Smith; M. G. Raymer

2007-12-09T23:59:59.000Z

436

Linear response theory in asymmetric nuclear matter for Skyrme functionals including spin-orbit and tensor terms  

E-Print Network [OSTI]

The formalism of linear response theory for a Skyrme functional including spin-orbit and tensor terms is generalized to the case of infinite nuclear matter with arbitrary isospin asymmetry. Response functions are obtained by solving an algebraic system of equations, which is explicitly given. Spin-isospin strength functions are analyzed varying the conditions of density, momentum transfer, asymmetry and temperature. The presence of instabilities, including the spinodal one, is studied by means of the static susceptibility.

D. Davesne; A. Pastore; J. Navarro

2014-02-18T23:59:59.000Z

437

United abominations: Density functional studies of heavy metal chemistry  

SciTech Connect (OSTI)

Carbonyl and nitrile addition to uranyl (UO{sup 2}{sup 2+}) are studied. The competition between nitrile and water ligands in the formation of uranyl complexes is investigated. The possibility of hypercoordinated uranyl with acetone ligands is examined. Uranyl is studied with diactone alcohol ligands as a means to explain the apparent hypercoordinated uranyl. A discussion of the formation of mesityl oxide ligands is also included. A joint theory/experimental study of reactions of zwitterionic boratoiridium(I) complexes with oxazoline-based scorpionate ligands is reported. A computational study was done of the catalytic hydroamination/cyclization of aminoalkenes with zirconium-based catalysts. Techniques are surveyed for programming for graphical processing units (GPUs) using Fortran.

Schoendorff, George

2012-04-02T23:59:59.000Z

438

Global hybrids from the semiclassical atom theory satisfying the local density linear response  

E-Print Network [OSTI]

We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 106, 186406, (2011)] yet employing an additional correlation functional which uses the localization concept of the correlation energy