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
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.
Error Analysis in Nuclear Density Functional Theory
Nicolas Schunck; Jordan D. McDonnell; Jason Sarich; Stefan M. Wild; Dave Higdon
2014-07-11T23:59:59.000Z
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.
Jain, Anubhav, Ph.D. Massachusetts Institute of Technology
2011-01-01T23:59:59.000Z
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, ...
Density Functional Theory (DFT) Simulated Annealing (SA)
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Fast and accurate direct MDCT to DFT conversion with arbitrary window functions
Paris-Sud XI, UniversitÃ© de
1 Fast and accurate direct MDCT to DFT conversion with arbitrary window functions Shuhua Zhang* and Laurent Girin Abstract--In this paper, we propose a method for direct con- version of MDCT coefficients of the MDCT-to- DFT conversion matrices into a Toeplitz part plus a Hankel part. The latter is split
Bjørnstad, Ottar Nordal
Stability of titanium oxide phases in Kohn-Sham density functional theory A well known problem of stability of titanium oxide phases at room temperature. That is, anatase instead of rutile is predicted as the room temperature phase for titanium oxide. In this work we try to establish the reasons
Yeo, Sang Chul
Ammonia (NH[subscript 3]) nitridation on an Fe surface was studied by combining density functional theory (DFT) and kinetic Monte Carlo (kMC) calculations. A DFT calculation was performed to obtain the energy barriers ...
Reformulation of DFT+U as a pseudo-hybrid Hubbard density functional Luis A. Agapito,1, 2
Curtarolo, Stefano
the true energy of the many-body system of the electrons and the approxi- mate energy that we can computeReformulation of DFT+U as a pseudo-hybrid Hubbard density functional Luis A. Agapito,1, 2 Stefano have seen two competing approaches unfold to address these problems: DFT+U and hybrid exact exchange
Periodic subsystem density-functional theory
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
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 Kohn–Sham 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 Kohn–Sham 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.
Screening for high-performance piezoelectrics using high-throughput density functional theory
Armiento, Rickard R.
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. ...
Progress at the interface of wave-function and density-functional theories
Gidopoulos, Nikitas I. [ISIS, Rutherford Appleton Laboratory, STFC, Didcot, OX11 0QX, Oxon (United Kingdom)
2011-04-15T23:59:59.000Z
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.
Singlet-Triplet Energy Gaps for Diradicals from Fractional-Spin Density-Functional Theory
Ess, Daniel H.; Johnson, E R; Hu, Xiangqian; Yang, W T
2011-01-01T23:59:59.000Z
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.
Javier, Alnald Caintic
2013-08-05T23:59:59.000Z
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...
Propagation of uncertainties in the nuclear DFT models
Markus Kortelainen
2014-09-04T23:59:59.000Z
Parameters of the nuclear density functional theory (DFT) models are usually adjusted to experimental data. As a result they carry certain theoretical error, which, as a consequence, carries out to the predicted quantities. In this work we address the propagation of theoretical error, within the nuclear DFT models, from the model parameters to the predicted observables. In particularly, the focus is set on the Skyrme energy density functional models.
Uncertainty Quantification and Propagation in Nuclear Density Functional Theory
N. Schunck; J. D. McDonnell; D. Higdon; J. Sarich; S. M. Wild
2015-03-19T23:59:59.000Z
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.
Density functional theory based generalized effective fragment potential method
Nguyen, Kiet A., E-mail: kiet.nguyen@wpafb.af.mil, E-mail: ruth.pachter@wpafb.af.mil [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., Dayton, Ohio 45432 (United States); Pachter, Ruth, E-mail: kiet.nguyen@wpafb.af.mil, E-mail: ruth.pachter@wpafb.af.mil [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Day, Paul N. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); General Dynamics Information Technology, Inc., Dayton, Ohio 45431 (United States)
2014-06-28T23:59:59.000Z
We present a generalized Kohn-Sham (KS) density functional theory (DFT) based effective fragment potential (EFP2-DFT) method for the treatment of solvent effects. Similar to the original Hartree-Fock (HF) based potential with fitted parameters for water (EFP1) and the generalized HF based potential (EFP2-HF), EFP2-DFT includes electrostatic, exchange-repulsion, polarization, and dispersion potentials, which are generated for a chosen DFT functional for a given isolated molecule. The method does not have fitted parameters, except for implicit parameters within a chosen functional and the dispersion correction to the potential. The electrostatic potential is modeled with a multipolar expansion at each atomic center and bond midpoint using Stone's distributed multipolar analysis. The exchange-repulsion potential between two fragments is composed of the overlap and kinetic energy integrals and the nondiagonal KS matrices in the localized molecular orbital basis. The polarization potential is derived from the static molecular polarizability. The dispersion potential includes the intermolecular D3 dispersion correction of Grimme et al. [J. Chem. Phys. 132, 154104 (2010)]. The potential generated from the CAMB3LYP functional has mean unsigned errors (MUEs) with respect to results from coupled cluster singles, doubles, and perturbative triples with a complete basis set limit (CCSD(T)/CBS) extrapolation, of 1.7, 2.2, 2.0, and 0.5 kcal/mol, for the S22, water-benzene clusters, water clusters, and n-alkane dimers benchmark sets, respectively. The corresponding EFP2-HF errors for the respective benchmarks are 2.41, 3.1, 1.8, and 2.5 kcal/mol. Thus, the new EFP2-DFT-D3 method with the CAMB3LYP functional provides comparable or improved results at lower computational cost and, therefore, extends the range of applicability of EFP2 to larger system sizes.
Subsystem real-time Time Dependent Density Functional Theory
Krishtal, Alisa; Pavanello, Michele
2015-01-01T23:59:59.000Z
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.
Density Functional Resonance Theory of Unbound Electronic Systems
Daniel L. Whitenack; Adam Wasserman
2011-06-20T23:59:59.000Z
Density Functional Resonance Theory (DFRT) is a complex-scaled version of ground-state Density Functional Theory (DFT) that allows one to calculate the resonance energies and lifetimes of metastable anions. In this formalism, the exact energy and lifetime of the lowest-energy resonance of unbound systems is encoded into a complex "density" that can be obtained via complex-coordinate scaling. This complex density is used as the primary variable in a DFRT calculation just as the ground-state density would be used as the primary variable in DFT. As in DFT, there exists a mapping of the N-electron interacting system to a Kohn-Sham system of N non-interacting particles in DFRT. This mapping facilitates self consistent calculations with an initial guess for the complex density, as illustrated with an exactly-solvable model system. Whereas DFRT yields in principle the exact resonance energy and lifetime of the interacting system, we find that neglecting the complex-correlation contribution leads to errors of similar magnitude to those of standard scattering close-coupling calculations under the bound-state approximation.
Density functional theory study of mercury adsorption on metal surfaces
Steckel, J.A.
2008-01-01T23:59:59.000Z
Density functional theory #1;DFT#2; calculations are used to characterize the interaction of mercury with copper, nickel, palladium, platinum, silver, and gold surfaces. Mercury binds relatively strongly to all the metal surfaces studied, with binding energies up to #3;1 eV for Pt and Pd. DFT calculations underestimate the energy of adsorption with respect to available experimental data. Plane-wave DFT results using the local density approximation and the Perdew-Wang 1991 and Perdew-Burke-Ernzerhof parametrizations of the generalized gradient approximation indicate that binding of mercury at hollow sites is preferred over binding at top or bridge sites. The interaction with mercury in order of increasing reactivity over the six metals studied is Ag #1;Au#1;Cu#1;Ni#1;Pt#1;Pd. Binding is stronger on the #1;001#2; faces of the metal surfaces, where mercury is situated in fourfold hollow sites as opposed to the threefold hollow sites on #1;111#2; faces. In general, mercury adsorption leads to decreases in the work function; adsorbate-induced work function changes are particularly dramatic on Pt.
Ceder, Gerbrand
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 ...
Solovyeva, Alisa [Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Technical University Braunschweig, Institute for Physical and Theoretical Chemistry, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany); Pavanello, Michele [Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Neugebauer, Johannes [Technical University Braunschweig, Institute for Physical and Theoretical Chemistry, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany)
2012-05-21T23:59:59.000Z
Subsystem density-functional theory (DFT) is a powerful and efficient alternative to Kohn-Sham DFT for large systems composed of several weakly interacting subunits. Here, we provide a systematic investigation of the spin-density distributions obtained in subsystem DFT calculations for radicals in explicit environments. This includes a small radical in a solvent shell, a {pi}-stacked guanine-thymine radical cation, and a benchmark application to a model for the special pair radical cation, which is a dimer of bacteriochlorophyll pigments, from the photosynthetic reaction center of purple bacteria. We investigate the differences in the spin densities resulting from subsystem DFT and Kohn-Sham DFT calculations. In these comparisons, we focus on the problem of overdelocalization of spin densities due to the self-interaction error in DFT. It is demonstrated that subsystem DFT can reduce this problem, while it still allows to describe spin-polarization effects crossing the boundaries of the subsystems. In practical calculations of spin densities for radicals in a given environment, it may thus be a pragmatic alternative to Kohn-Sham DFT calculations. In our calculation on the special pair radical cation, we show that the coordinating histidine residues reduce the spin-density asymmetry between the two halves of this system, while inclusion of a larger binding pocket model increases this asymmetry. The unidirectional energy transfer in photosynthetic reaction centers is related to the asymmetry introduced by the protein environment.
DFT --Das Future Tool ``Das Future Tool'' was the title of the group T-shirt1 that we
Ziegler, Tom
TRIBUTE DFT -- Das Future Tool ``Das Future Tool'' was the title of the group T-shirt1 that we had article ``Approximate Density Functional Theory as a Practical Tool in Molecular Energetics and Dynamics and considered it just another semi-empirical method.2 Tom, however, realized that DFT was ``Das Future Tool
Quantification of Uncertainties in Nuclear Density Functional theory
N. Schunck; J. D. McDonnell; D. Higdon; J. Sarich; S. Wild
2014-09-17T23:59:59.000Z
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.
Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems
Bokareva, Olga S; Bokarev, Sergey I; Kühn, Oliver
2015-01-01T23:59:59.000Z
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.
Pfeifer, Holger
Adsorption of small aromatic molecules on the ,,111... surfaces of noble metals: A density 10 May 2010; published online 10 June 2010 The adsorption of benzene, thiophene, and pyridine on the 111 surface of gold and copper have been studied using density functional theory DFT . Adsorption
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
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.
Bankura, Arindam; DiStasio, Robert A; Swartz, Charles W; Klein, Michael L; Wu, Xifan
2015-01-01T23:59:59.000Z
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...
approximate dft method: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
method for the calculation of the electronic in the success of DFT The optimization of new functionals depends on two factors: the functional form must of the...
Parallel Implementation of Gamma-Point Pseudopotential Plane-Wave DFT with Exact Exchange
Bylaska, Eric J.; Tsemekhman, Kiril L.; Baden, Scott B.; Weare, John H.; Jonsson, Hannes
2011-01-15T23:59:59.000Z
One of the more persistent failures of conventional density functional theory (DFT) methods has been their failure to yield localized charge states such as polarons, excitons and solitons in solid-state and extended systems. It has been suggested that conventional DFT functionals, which are not self-interaction free, tend to favor delocalized electronic states since self-interaction creates a Coulomb barrier to charge localization. Pragmatic approaches in which the exchange correlation functionals are augmented with small amount of exact exchange (hybrid-DFT, e.g. B3LYP and PBE0) have shown promise in localizing charge states and predicting accurate band gaps and reaction barriers. We have developed a parallel algorithm for implementing exact exchange into pseudopotential plane-wave density functional theory and we have implemented it in the NWChem program package. The technique developed can readily be employed in plane-wave DFT programs. Furthermore, atomic forces and stresses are straightforward to implement, making it applicable to both confined and extended systems, as well as to Car-Parrinello ab initio molecular dynamic simulations. This method has been applied to several systems for which conventional DFT methods do not work well, including calculations for band gaps in oxides and the electronic structure of a charge trapped state in the Fe(II) containing mica, annite.
Fast plane wave density functional theory molecular dynamics calculations on multi-GPU machines
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
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.
Arindam Bankura; Biswajit Santra; Robert A. DiStasio Jr.; Charles W. Swartz; Michael L. Klein; Xifan Wu
2015-03-25T23:59:59.000Z
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.
Ramachandran, Arathi
2012-01-01T23:59:59.000Z
Efficient utilization of the sun as a renewable and clean energy source is one of the greatest goals and challenges of this century due to the increasing demand for energy and its environmental impact. Photoactive molecules ...
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
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.
Hexakis(4-phormylphenoxy)cyclotriphosphazene: X-ray and DFT-calculated structures
Albayrak, Cigdem, E-mail: calbayrak@sinop.edu.tr; Kosar, Basak [Sinop University, Faculty of Education (Turkey); Odabasoglu, Mustafa [Pamukkale University, Chemical Technology Program (Turkey); Bueyuekguengoer, Orhan [Ondokuz Mayis University, Faculty of Arts and Sciences (Turkey)
2010-12-15T23:59:59.000Z
The crystal structure of hexakis(4-phormylphenoxy)cyclotriphosphazene is determined by using X-ray diffraction and then the molecular structure is investigated with density functional theory (DFT). X-Ray study shows that the title compound has C-H-{pi} interaction with phosphazene ring. The molecules in the unit cell are packed with Van der Waals and dipole-dipole interactions and the molecules are packed in zigzag shaped. Optimized molecular geometry is calculated with DFT at B3LYP/6-311G(d,p) level. The results from both experimental and theoretical calculations are compared in this study.
Ferromagnetism in GaN: Gd: A density functional theory study
Stevenson, Cynthia; Stevenson, Cynthia
2008-02-04T23:59:59.000Z
First principle calculations of the electronic structure and magnetic interaction of GaN:Gd have been performed within the Generalized Gradient Approximation (GGA) of the density functional theory (DFT) with the on-site Coulomb energy U taken into account (also referred to as GGA+U). The ferromagnetic p-d coupling is found to be over two orders of magnitude larger than the s-d exchange coupling. The experimental colossal magnetic moments and room temperature ferromagnetism in GaN:Gd reported recently are explained by the interaction of Gd 4f spins via p-d coupling involving holes introduced by intrinsic defects such as Ga vacancies.
SCALING RELATIONS IN DENSITY FUNCTIONAL THEORY AND
Burke, Kieron
are being made to apply DFT to systems of bio- logical interest that would otherwise be unfeasible with traditional wavefunction methods. Although much of present research in DFT development focuses on an extension to the study of models for organometallic catalysts used in the dehydrogenation of alkanes to form alkenes
Jacek Dobaczewski Density functional theory and energy
Dobaczewski, Jacek
in Poland per voivodship Energy density functional 245 647 Price voivodship functional 654 763 295 580Jacek Dobaczewski Density functional theory and energy density functionals in nuclear physics Jacek://www.fuw.edu.pl/~dobaczew/Stellenbosch/dobaczewski_lecture.pdf Home page: http://www.fuw.edu.pl/~dobaczew/ #12;Jacek Dobaczewski Nuclear Structure Energy scales
Biswajit Santra; Ji?í Klimeš; Alexandre Tkatchenko; Dario Alfè; Ben Slater; Angelos Michaelides; Roberto Car; Matthias Scheffler
2014-08-14T23:59:59.000Z
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.
Van der Waals density-functional theory study for bulk solids with BCC, FCC, and diamond structures
Park, Jinwoo; Hong, Suklyun
2015-01-01T23:59:59.000Z
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.
Functional Integration for Quantum Field Theory
J. LaChapelle
2006-10-16T23:59:59.000Z
The functional integration scheme for path integrals advanced by Cartier and DeWitt-Morette is extended to the case of fields. The extended scheme is then applied to quantum field theory. Several aspects of the construction are discussed.
Adsorption of silver dimer on graphene - A DFT study
Kaur, Gagandeep, E-mail: gaganj1981@yahoo.com [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and Chandigarh Engineering College, Landran, Mohali-140307, Punjab (India); Gupta, Shuchi [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and University Institute of Engineering and Technology, Panjab University, Chandigarh -160014 (India); Rani, Pooja; Dharamvir, Keya [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014 (India)
2014-04-24T23:59:59.000Z
We performed a systematic density functional theory (DFT) study of the adsorption of silver dimer (Ag{sub 2}) on graphene using SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Ag2-graphene system are calculated. The minimum energy configuration for a silver dimer is parallel to the graphene sheet with its two atoms directly above the centre of carbon-carbon bond. The negligible charge transfer between the dimer and the surface is also indicative of a weak bond. The methodology demonstrated in this paper may be applied to larger silver clusters on graphene sheet.
Quantum critical benchmark for density functional theory
Paul E. Grabowski; Kieron Burke
2014-08-09T23:59:59.000Z
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.
Magnetic fields and density functional theory
Salsbury Jr., Freddie
1999-02-01T23:59:59.000Z
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.
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your1 SECTION A. Revised:7,A Search for muonMiniDFT MiniDFT
Fragment Approach to Constrained Density Functional Theory Calculations using Daubechies Wavelets
Ratcliff, Laura E; Mohr, Stephan; Deutsch, Thierry
2015-01-01T23:59:59.000Z
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...
A Density Functional Theory Study of Formaldehyde Adsorption...
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Density Functional Theory Study of Formaldehyde Adsorption on Ceria. A Density Functional Theory Study of Formaldehyde Adsorption on Ceria. Abstract: Molecular adsorption of...
Density Functional Theory Study of Oxygen Reduction Activity...
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Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes. Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum...
Density functional theory for carbon dioxide crystal
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
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.
Silvestrelli, Pier Luigi; Ambrosetti, Alberto [Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I–35131 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, Università di Padova, via Marzolo 8, I–35131 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
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.
Higher-order finite-difference formulation of periodic Orbital-free Density Functional Theory
Ghosh, Swarnava
2014-01-01T23:59:59.000Z
We present a real-space formulation and higher-order finite-difference implementation of periodic Orbital-free Density Functional Theory (OF-DFT). Specifically, utilizing a local reformulation of the electrostatic and kernel terms, we develop a generalized framework suitable for performing OF-DFT simulations with different variants of the electronic kinetic energy. In particular, we develop a self-consistent field (SCF) type fixed-point method for calculations involving linear-response kinetic energy functionals. In doing so, we make the calculation of the electronic ground-state and forces on the nuclei amenable to computations that altogether scale linearly with the number of atoms. We develop a parallel implementation of this formulation using the finite-difference discretization, using which we demonstrate that higher-order finite-differences can achieve relatively large convergence rates with respect to mesh-size in both the energies and forces. Additionally, we establish that the fixed-point iteration c...
Thermally-assisted-occupation density functional theory with generalized-gradient approximations
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
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.
Density Functional Theory Models for Radiation Damage
Density Functional Theory Models for Radiation Damage S.L. Dudarev EURATOM/CCFE Fusion Association and informative as the most advanced experimental techniques developed for the observation of radiation damage investigation and assessment of radiation damage effects, offering new insight into the origin of temperature
Higher-order adaptive finite-element methods for Kohn–Sham density functional theory
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
We present an efficient computational approach to perform real-space electronic structure calculations using an adaptive higher-order finite-element discretization of Kohn–Sham 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 Gauss–Lobatto quadrature, and a Chebyshev acceleration technique for computing the occupied eigenspace. The proposed approach has been observed to provide a staggering 100–200-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 Kohn–Sham DFT problem. Our studies suggest that staggering computational savings—of the order of 1000-fold—relative 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 Kohn–Sham 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.
Schwinger functions in noncommutative quantum field theory
Dorothea Bahns
2009-08-31T23:59:59.000Z
It is shown that the $n$-point functions of scalar massive free fields on the noncommutative Minkowski space are distributions which are boundary values of analytic functions. Contrary to what one might expect, this construction does not provide a connection to the popular traditional Euclidean approach to noncommutative field theory (unless the time variable is assumed to commute). Instead, one finds Schwinger functions with twistings involving only momenta that are on the mass-shell. This explains why renormalization in the traditional Euclidean noncommutative framework crudely differs from renormalization in the Minkowskian regime.
Maeta, Takahiro [Graduate School of System Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan); GlobalWafers Japan Co., Ltd., Higashikou, Seirou-machi, Kitakanbara-gun, Niigata 957-0197 (Japan); Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan)
2014-08-21T23:59:59.000Z
Ge-based substrates are being developed for applications in advanced nano-electronic devices because of their higher intrinsic carrier mobility than Si. The stability and diffusion mechanism of impurity atoms in Ge are not well known in contrast to those of Si. Systematic studies of the stable sites of 2nd to 6th row element impurity atoms in Ge crystal were undertaken with density functional theory (DFT) and compared with those in Si crystal. It was found that most of the impurity atoms in Ge were stable at substitutional sites, while transition metals in Si were stable at interstitial sites and the other impurity atoms in Si were stable at substitutional sites. Furthermore, DFT calculations were carried out to clarify the mechanism responsible for the diffusion of impurity atoms in Ge crystals. The diffusion mechanism for 3d transition metals in Ge was found to be an interstitial-substitutional diffusion mechanism, while in Si this was an interstitial diffusion mechanism. The diffusion barriers in the proposed diffusion mechanisms in Ge and Si were quantitatively verified by comparing them to the experimental values in the literature.
Mehdi Farzanehpour; I. V. Tokatly
2015-06-29T23:59:59.000Z
We use analytic (current) density-potential maps of time-dependent (current) density functional theory (TD(C)DFT) to inverse engineer analytically solvable time-dependent quantum problems. In this approach the driving potential (the control signal) and the corresponding solution of the Schr\\"odinger equation are parametrized analytically in terms of the basic TD(C)DFT observables. We describe the general reconstruction strategy and illustrate it with a number of explicit examples. First we consider the real space one-particle dynamics driven by a time-dependent electromagnetic field and recover, from the general TDDFT reconstruction formulas, the known exact solution for a driven oscillator with a time-dependent frequency. Then we use analytic maps of the lattice TD(C)DFT to control quantum dynamics in a discrete space. As a first example we construct a time-dependent potential which generates prescribed dynamics on a tight-binding chain. Then our method is applied to the dynamics of spin-1/2 driven by a time dependent magnetic field. We design an analytic control pulse that transfers the system from the ground to excited state and vice versa. This pulse generates the spin flip thus operating as a quantum NOT gate.
Krishtal, Alisa; Genova, Alessandro; Pavanello, Michele
2015-01-01T23:59:59.000Z
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.
Mattsson, Ann Elisabet
2012-01-01T23:59:59.000Z
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.
Density Functional Theory Studies of the Electronic Structure...
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Theory Studies of the Electronic Structure of Solid State Actinide Oxides. Density Functional Theory Studies of the Electronic Structure of Solid State Actinide Oxides. Abstract:...
Nuclear fission in covariant density functional theory
A. V. Afanasjev; H. Abusara; P. Ring
2013-09-12T23:59:59.000Z
The current status of the application of covariant density functional theory to microscopic description of nuclear fission with main emphasis on superheavy nuclei (SHN) is reviewed. The softness of SHN in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers of SHN are considerably affected both by triaxiality and octupole deformation.
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
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.
Theoretical Chemistry Theory, Computation, and
Gherman, Benjamin F.
1 23 Theoretical Chemistry Accounts Theory, Computation, and Modeling ISSN 1432-881X Volume 128). In order to explore the origin of this preference, density functional theory (DFT) calculations have been-terminus of nascent eubacterial proteins during protein synthesis [14]. As PDF is essential for bacterial survival
Symmetry energy in nuclear density functional theory
W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar
2013-07-22T23:59:59.000Z
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.
Triplet absorption in carbon nanotubes: a TD-DFT study
Sergei Tretiak
2007-02-13T23:59:59.000Z
We predict properties of triplet excited states in single-walled carbon nanotubes (CNTs) using a time-dependent density-functional theory (TD-DFT). We show that the lowest triplet state energy in CNTs to be about 0.2-0.3 eV lower than the lowest singlet states. Like in $\\pi$-conjugated polymers, the lowest CNT triplets are spatially localized. These states show strong optical absorption at about 0.5-0.6 eV to the higher lying delocalized triplet states. These results demonstrate striking similarity of the electronic features between CNTs and $\\pi$-conjugated polymers and provide explicit guidelines for spectroscopic detection of CNT triplet states.
Band terminations in density functional theory
A. V. Afanasjev
2009-02-01T23:59:59.000Z
The analysis of the terminating bands has been performed in the relativistic mean field framework. It was shown that nuclear magnetism provides an additional binding to the energies of the specific configuration and this additional binding increases with spin and has its {\\it maximum} exactly at the terminating state. This suggests that the terminating states can be an interesting probe of the time-odd mean fields {\\it provided that other effects can be reliably isolated.} Unfortunately, a reliable isolation of these effects is not that simple: many terms of the density functional theories contribute into the energies of the terminating states and the deficiencies in the description of those terms affect the result. The recent suggestion \\cite{ZSW.05} that the relative energies of the terminating states in the $N \
Theory and Computation | Center for Functional Nanomaterials
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Theory and Computation theory and computation Flexible computational infrastructure, software tools and theoretical consultation are provided to support modeling and understanding...
Tawa, G.J.; Martin, R.L.; Pratt, L.R.; Russo, T.V. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States)
1996-02-01T23:59:59.000Z
Electrostatic solvation free energies are calculated using a self consistent reaction field (SCRF) procedure that combines a continuum dielectric model of the solvent with both Hartree-Fock (HF) and density functional theory (DFT) for the solute. Several molecules are studied in aqueous solution. They comprise three groups: nonpolar neutral, polar neutral, and ionic. The calculated values of {Delta}G{sup e1} are sensitive to the atomic radii used to define the solute molecular surface, particularly to the value of the hydrogen radius. However, the values of {Delta}G{sup e1} exhibit reasonable correlation with experiment when a previously determined, physically motivated set of atomic radii were used to define the van der Waals surface of the solute. The standard deviation between theory and experiment is 2.51 kcal/mol for HF and 2.21 kcal/mol for DFT for the 14 molecules examined. The errors with HF or DFT are similar. The relative difference between the calculated values of {Delta}G{sup e1} and experiment is largest for nonpolar neutral molecules, intermediate for polar neutral molecules, and smallest for ions. This is consistent with the expected relative importance of nonelectrostatic contributions to the free energy that are omitted in the model. 92 refs., 4 figs., 6 tabs.
Sussman, Joel L.
Taiyuan Road, Shanghai 200031, P. R. China, and Departments of Structural Biology and Neurobiology, NH4 + always tilts toward the carbon-carbon bond rather than toward the heteroatom or the carbon
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
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.
Density Functional Theory Studies of Magnetically Confined Fermi Gas
Chen, Y J; Chen, Yu-Jun
2001-01-01T23:59:59.000Z
A theory is developed for magnetically confined Fermi gas at low temperature based on the density functional theory. The theory is illustrated by numerical calculation of density distributions of Fermi atoms $^{40}$K with parameters according to DeMarco and Jin's experiment[Science, 285(1999)1703]. Our results are in good agreement with the experiment. To check the theory, we also performed calculations using our theory at high temperature and compared very well to the result of classical limit.
Magnetic fields and density functional theory
Jr, F.-Salsbury
2010-01-01T23:59:59.000Z
development of the general theory, Grayce and Harris used an electron gas approach to obtain a local energy
The vacuum state functional of interacting string field theory
A. Ilderton
2005-06-21T23:59:59.000Z
We show that the vacuum state functional for both open and closed string field theories can be constructed from the vacuum expectation values it must generate. The method also applies to quantum field theory and as an application we give a diagrammatic description of the equivalance between Schrodinger and covariant repreresentations of field theory.
Soderlind, P; Wolfer, W
2007-07-27T23:59:59.000Z
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.
I. A. Shkrob
2006-07-25T23:59:59.000Z
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.
Ensemble density variational methods with self- and ghost-interaction-corrected functionals
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
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.
Optimized multi-site local orbitals in the large-scale DFT program CONQUEST
Nakata, Ayako; Miyazaki, Tsuyoshi
2015-01-01T23:59:59.000Z
We introduce numerical optimization of multi-site support functions in the linear-scaling DFT code CONQUEST. Multi-site support functions, which are linear combinations of pseudo-atomic orbitals on a target atom and those neighbours within a cutoff, have been recently proposed to reduce the number of support functions to the minimal basis while keeping the accuracy of a large basis [J. Chem. Theory Comput., 2014, 10, 4813]. The coefficients were determined by using the local filter diagonalization (LFD) method [Phys. Rev. B, 2009, 80, 205104]. We analyse the effect of numerical optimization of the coefficients produced by the LFD method. Tests on crystalline silicon, a benzene molecule and hydrated DNA systems show that the optimization improves the accuracy of the multi-site support functions with small cutoffs. It is also confirmed that the optimization guarantees the variational energy minimizations with multi-site support functions.
Optimal Transportation Theory with Repulsive Costs
Simone Di Marino; Augusto Gerolin; Luca Nenna
2015-06-15T23:59:59.000Z
This paper intents to present the state of art and recent developments of the optimal transportation theory with many marginals for a class of repulsive cost functions. We introduce some aspects of the Density Functional Theory (DFT) from a mathematical point of view, and revisit the theory of optimal transport from its perspective. Moreover, in the last three sections, we describe some recent and new theoretical and numerical results obtained for the Coulomb cost, the repulsive harmonic cost and the determinant cost.
(E)-2-[(2-Bromophenylimino)methyl]-5-methoxyphenol: X-ray and DFT-calculated structures
Kosar, B., E-mail: bkosar@omu.edu.tr; Albayrak, C. [Sinop University, Faculty of Education (Turkey); Odabasoglu, M. [Pamukkale University, Chemistry Program (Turkey); Bueyuekguengoer, O. [Ondokuz Mayis University, Faculty of Arts and Sciences (Turkey)
2010-12-15T23:59:59.000Z
The crystal structure of (E)-2-[(2-Bromophenylimino)methyl]-5-methoxyphenol is determined by using X-ray diffraction and then the molecular structure is investigated with density functional theory (DFT). X-Ray study shows that the title compound has a strong intramolecular O-H-N hydrogen bond and three dimensional crystal structure is primarily determined by C-H-{pi} and weak van der Waals interactions. The strong O-H-N bond is an evidence of the preference for the phenol-imine tautomeric form in the solid state. Optimized molecular geometry is calculated with DFT at the B3LYP/6-31G(d,p) level. The IR spectra of compound were recorded experimentally and calculated to compare with each other. The results from both experiment and theoretical calculations are compared in this study.
On Painleve Related Functions Arising in Random Matrix Theory
Leonard N. Choup
2011-01-27T23:59:59.000Z
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.
A COMPLEXITY THEORY OF CONSTRUCTIBLE FUNCTIONS AND ...
2014-09-30T23:59:59.000Z
Sep 30, 2014 ... Primary 14P10, 14P25; Secondary 68W30. Key words and phrases. constructible functions, constructible sheaves, polynomial hierarchy,.
Desjarlais, Michael Paul; Mattsson, Thomas Kjell Rene
2006-03-01T23:59:59.000Z
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.
Constrained Density-Functional Theory--Configuration Interaction
Kaduk, Benjamin James
2012-01-01T23:59:59.000Z
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 ...
Classical density functional theory to tackle solvation in molecular liquids
Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel
2015-01-01T23:59:59.000Z
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.
Density Functional Theory with Dissipation: Transport through Single Molecules
Kieron Burke
2012-04-30T23:59:59.000Z
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.
Preface: Special Topic on Advances in Density Functional Theory
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
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.
Test Functions Space in Noncommutative Quantum Field Theory
M. Chaichian; M. Mnatsakanova; A. Tureanu; Yu. Vernov
2008-07-26T23:59:59.000Z
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.
Pair densities in density functional theory
Chen, Huajie
2015-01-01T23:59:59.000Z
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...
Ulian, Gianfranco; Valdrè, Giovanni, E-mail: giovanni.valdre@unibo.it [Dipartimento di Scienze Biologiche e Geologico-Ambientali, Centro di Ricerca Interdisciplinare di Biomineralogia, Cristallografia e Biomateriali, Università 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, Università di Bologna “Alma Mater Studiorum” Piazza di Porta San Donato 1, 40126 Bologna (Italy); Tosoni, Sergio [Departament de Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)] [Departament de Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)
2013-11-28T23:59:59.000Z
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.
Impact of local stacking on the graphene-impurity interaction: theory and experiments
Paris-Sud XI, Université de
Impact of local stacking on the graphene-impurity interaction: theory and experiments F. Hiebel, P (Dated: January 16, 2014) We investigate the graphene-impurity interaction problem by combining impurity model and density functional theory (DFT) calculations - techniques. We use graphene on the Si
Density Functional Theory-Based Database Development and CALPHAD Automation
Chen, Long-Qing
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
Monte Carlo tests of Orbital-Free Density Functional Theory
D. I. Palade
2014-12-12T23:59:59.000Z
The relationship between the exact kinetic energy density in a quantum system in the frame of Density Functional Theory and the semiclassical functional expression for the same quantity is investigated. The analysis is performed with Monte Carlo simulations of the Kohn-Sham potentials. We find that the semiclassical form represents the statistical expectation value of the quantum nature. Based on the numerical results, we propose an empirical correction to the existing functional and an associated method to improve the Orbital-Free results.
Addressing spectroscopic quality of covariant density functional theory
A. V. Afanasjev
2014-09-17T23:59:59.000Z
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.
Sorkin, Anastassia; Iron, Mark A.; Truhlar, Donald G.
2008-02-01T23:59:59.000Z
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 (öe). 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 (ð or ä) is partially occupied in the 4¼ 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.
Multi-time wave functions for quantum field theory
Petrat, Sören, E-mail: petrat@math.lmu.de [Mathematisches Institut, Ludwig-Maximilians-Universität, Theresienstr. 39, 80333 München (Germany); Tumulka, Roderich, E-mail: tumulka@math.rutgers.edu [Department of Mathematics, Rutgers University, 110 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States)
2014-06-15T23:59:59.000Z
Multi-time wave functions such as ?(t{sub 1},x{sub 1},…,t{sub N},x{sub N}) have one time variable t{sub j} for each particle. This type of wave function arises as a relativistic generalization of the wave function ?(t,x{sub 1},…,x{sub N}) of non-relativistic quantum mechanics. We show here how a quantum field theory can be formulated in terms of multi-time wave functions. We mainly consider a particular quantum field theory that features particle creation and annihilation. Starting from the particle–position representation of state vectors in Fock space, we introduce multi-time wave functions with a variable number of time variables, set up multi-time evolution equations, and show that they are consistent. Moreover, we discuss the relation of the multi-time wave function to two other representations, the Tomonaga–Schwinger representation and the Heisenberg picture in terms of operator-valued fields on space–time. In a certain sense and under natural assumptions, we find that all three representations are equivalent; yet, we point out that the multi-time formulation has several technical and conceptual advantages. -- Highlights: •Multi-time wave functions are manifestly Lorentz-covariant objects. •We develop consistent multi-time equations with interaction for quantum field theory. •We discuss in detail a particular model with particle creation and annihilation. •We show how multi-time wave functions are related to the Tomonaga–Schwinger approach. •We show that they have a simple representation in terms of operator valued fields.
Hu, Shenyang Y.; Setyawan, Wahyu; Van Ginhoven, Renee M.; Jiang, Weilin; Henager, Charles H.; Kurtz, Richard J.
2014-02-20T23:59:59.000Z
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.
Adam P. Hughes; Uwe Thiele; Andrew J. Archer
2015-01-28T23:59:59.000Z
The contribution to the free energy for a film of liquid of thickness $h$ on a solid surface, due to the interactions between the solid-liquid and liquid-gas interfaces is given by the binding potential, $g(h)$. The precise form of $g(h)$ determines whether or not the liquid wets the surface. Note that differentiating $g(h)$ gives the Derjaguin or disjoining pressure. We develop a microscopic density functional theory (DFT) based method for calculating $g(h)$, allowing us to relate the form of $g(h)$ to the nature of the molecular interactions in the system. We present results based on using a simple lattice gas model, to demonstrate the procedure. In order to describe the static and dynamic behaviour of non-uniform liquid films and drops on surfaces, a mesoscopic free energy based on $g(h)$ is often used. We calculate such equilibrium film height profiles and also directly calculate using DFT the corresponding density profiles for liquid drops on surfaces. Comparing quantities such as the contact angle and also the shape of the drops, we find good agreement between the two methods. We also study in detail the effect on $g(h)$ of truncating the range of the dispersion forces, both those between the fluid molecules and those between the fluid and wall. We find that truncating can have a significant effect on $g(h)$ and the associated wetting behaviour of the fluid.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Yamaoka, Hitoshi; Jarrige, Ignace; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; et al
2015-03-01T23:59:59.000Z
The electronic structure of Ce?Pd??X? (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f? (Ce??) component with a small fraction of f¹more »(Ce³?) component. The spectral weight of f¹ component near the Fermi level Ce?Pd??Si? is stronger than that for Ce?Pd??Ge? at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce?Pd??Si? compared to Ce?Pd??Ge?.« less
DFT Investigation of Osmium Terpyridinyl Complexes as Potential Optical Limiting Materials
Alok, Shashwat
2015-01-01T23:59:59.000Z
The development of optical power limiting materials is important to protect individuals or materials from intense laser irradiation. The photophysical behavior of Os(II) polypyridinyl complexes having aromatic hydrocarbon terpyridyl ligands has received considerable attention as systems exhibiting intramolecular energy transfer to yield a long excited states lifetime. Here we present a focused discussion to illustrate the photophysical behavior of transition metal complexes with modified terpyridyl ligands, utilizing density functional theory. Our DFT studies of the excited state behavior of Os(II) complexes containing pyrene-vinylene derived terpyridine (pyr-v-tpy) ligands can be applied to the development of optical limiting materials controlling the laser power at longer wavelength range.
Desnavi, Sameerah, E-mail: sameerah-desnavi@zhcet.ac.in [Department of Electronic Engineering, ZHCET, Aligarh Muslim University, Aligarh-202002 (India); Chakraborty, Brahmananda; Ramaniah, Lavanya M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)
2014-04-24T23:59:59.000Z
The electronic structure and hydrogen storage capability of Yttrium-doped grapheme has been theoretically investigated using first principles density functional theory (DFT). Yttrium atom prefers the hollow site of the hexagonal ring with a binding energy of 1.40 eV. Doping by Y makes the system metallic and magnetic with a magnetic moment of 2.11 ?{sub B}. Y decorated graphene can adsorb up to four hydrogen molecules with an average binding energy of 0.415 eV. All the hydrogen atoms are physisorbed with an average desorption temperature of 530.44 K. The Y atoms can be placed only in alternate hexagons, which imply a wt% of 6.17, close to the DoE criterion for hydrogen storage materials. Thus, this system is potential hydrogen storage medium with 100% recycling capability.
Symmetry Projected Density Functional Theory and Neutron Halo’s
unknown authors
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
Relativistic density functional theory for finite nuclei and neutron stars
J. Piekarewicz
2015-02-05T23:59:59.000Z
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.
Alam, Aftab [Ames Laboratory; Johnson, Duane D. [Ames Laboratory
2014-06-01T23:59:59.000Z
Cerium and its technologically relevant compounds are examples of anomalous mixed valency, originating from two competing oxidation states—itinerant 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.
A Self-Consistent Hubbard U Density-Functional Theory Approach...
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Self-Consistent Hubbard U Density-Functional Theory Approach to the Addition-Elimination Reactions of Hydrocarbons on Bare FeO A Self-Consistent Hubbard U Density-Functional Theory...
Descriptions of carbon isotopes within the energy density functional theory
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
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.
A Wigner Monte Carlo approach to density functional theory
Sellier, J.M., E-mail: jeanmichel.sellier@gmail.com; Dimov, I.
2014-08-01T23:59:59.000Z
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 (Kohn–Sham 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 Kohn–Sham systems provides a reliable computational tool which could, eventually, be applied to more sophisticated problems.
Excitations and benchmark ensemble density functional theory for two electrons
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
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.
Ye, Jingyun; Liu, Changjun; Mei, Donghai; Ge, Qingfeng
2014-08-01T23:59:59.000Z
Methanol synthesis from CO2 hydrogenation on Pd4/In2O3 has been investigated using density functional theory (DFT) and microkinetic modeling. In this study, three possible routes in the reaction network of CO2 + H2 ? CH3OH + H2O have been examined. Our DFT results show that the HCOO route competes with the RWGS route whereas a high activation barrier kinetically blocks the HCOOH route. DFT results also suggest that H2COO* + H* ? H2CO* +OH* and cis-COOH* + H* ?CO* + H2O* are the rate limiting steps in the HCOO route and the RWGS route, respectively. Microkinetic modeling results demonstrate that the HCOO route is the dominant reaction route for methanol synthesis from CO2 hydrogenation. We found that the activation of H adatom on the small Pd cluster and the presence of H2O on the In2O3 substrate play important roles in promoting the methanol synthesis. The hydroxyl adsorbed at the interface of Pd4/In2O3 induces the transformation of the supported Pd4 cluster from a butterfly structure into a tetrahedron structure. This important structure change not only indicates the dynamical nature of the supported nanoparticle catalyst structure during the reaction but also shifts the final hydrogenation step from H2COH to CH3O.
Jackson, Virgil E.; Gutowski, Keith E.; Dixon, David A.
2013-09-12T23:59:59.000Z
The structures, vibrational frequencies and energetics of anhydrous and hydrated complexes of UO2 2+ with the phosphate anions H2PO4 ?, HPO4 2?, and PO4 3? were predicted at the density functional theory (DFT) and MP2 molecular orbital theory levels as isolated gas phase species and in aqueous solution by using self-consistent reaction field (SCRF) calculations with different solvation models. The geometries and vibrational frequencies of the major binding modes for these complexes are compared to experiment where possible and good agreement is found. The uranyl moiety is nonlinear in many of the complexes, and the coordination number (CN) 5 in the equatorial plane is the predominant binding motif. The phosphates are found to bind in both monodentate and bidentate binding modes depending on the charge and the number of water molecules. The SCRF calculations were done with a variety of approaches, and different SCRF approaches were found to be optimal for different reaction types. The acidities of HxPO4 3?x in HxPO4 3?x(H2O)4, x = 0?3 complexes were calculated with different SCRF models and compared to experiment. Phosphate anions can displace water molecules from the first solvation shell at the uranyl exothermically. The addition of water molecules can cause the bonding of H2PO4 ? and HPO4 2? to change from bidentate to monodentate exothermically while maintaining CN 5. The addition of water can generate monodentate structures capable of cross-linking to other uranyl phosphates to form the types of structures found in the solid state. [UO2(HPO4)(H2O)3] is predicted to be a strong base in the gas phase and in aqueous solution. It is predicted to be a much weaker acid than H3PO4 in the gas phase and in solution.
The intrapair electron correlation in natural orbital functional theory
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
A previously proposed [M. Piris, X. Lopez, F. Ruipérez, 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.
Phonons and related crystal properties from density-functional perturbation theory
Wu, Zhigang
-Functional Perturbation Theory 516 A. Lattice dynamics from electronic-structure theory 516 B. Density-functional theory July 2001) This article reviews the current status of lattice-dynamical calculations in crystals, using specialized topics are treated, including the implementation for metals, the calculation of the response
Lao, Ka Un; Herbert, John M., E-mail: herbert@chemistry.ohio-state.edu [Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210 (United States)
2014-01-28T23:59:59.000Z
The performance of second-order symmetry-adapted perturbation theory (SAPT) calculations using Kohn-Sham (KS) orbitals is evaluated against benchmark results for intermolecular interactions. Unlike previous studies of this “SAPT(KS)” methodology, the present study uses non-empirically tuned long-range corrected (LRC) functionals for the monomers. The proper v{sub xc} (r)?0 asymptotic limit is achieved by tuning the range separation parameter in order to satisfy the condition that the highest occupied KS energy level equals minus the molecule's ionization energy, for each monomer unit. Tests for He{sub 2}, Ne{sub 2}, and the S22 and S66 data sets reveal that this condition is important for accurate prediction of the non-dispersion components of the energy, although errors in SAPT(KS) dispersion energies remain unacceptably large. In conjunction with an empirical dispersion potential, however, the SAPT(KS) method affords good results for S22 and S66, and also accurately predicts the whole potential energy curve for the sandwich isomer of the benzene dimer. Tuned LRC functionals represent an attractive alternative to other asymptotic corrections that have been employed in density-functional-based SAPT calculations, and we recommend the use of tuned LRC functionals in both coupled-perturbed SAPT(DFT) calculations and dispersion-corrected SAPT(KS) calculations.
Self-interaction corrections in density functional theory
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
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 Weizsäcker 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.
Supplementary data for "Relativistic density functional theory modeling of plutonium and
Titov, Anatoly
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
Moreira, E. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Henriques, J.M. [Centro de Educacao e Saude, Universidade Federal de Campina Grande, Campus Cuite, 58175-000 Cuite-PB (Brazil); Azevedo, D.L. [Departamento de Fisica, Universidade Federal do Maranhao, Centro de Ciencias Exatas e Tecnologia, 65085-580 Sao Luis-MA (Brazil); Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Caetano, E.W.S., E-mail: ewcaetano@gmail.co [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara, Av. 13 de Maio, 2081, Benfica, 60040-531 Fortaleza-CE (Brazil); Freire, V.N. [Departamento de Fisica, Universidade Federal do Ceara, Centro de Ciencias, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza-CE (Brazil); Albuquerque, E.L. [Departamento de Biofisica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)
2011-04-15T23:59:59.000Z
Orthorhombic SrSnO{sub 3} was investigated using density functional theory (DFT) considering both the local density and generalized gradient approximations, LDA and GGA, respectively. The electronic band structure, density of states, complex dielectric function, optical absorption, and the infrared and Raman spectra were computed. Calculated lattice parameters are close to the experimental measurements, and an indirect band gap E(S{yields}{Gamma})=1.97eV (2.27 eV) was obtained within the GGA (LDA) level of calculation. Effective masses for holes and electrons were estimated, being very anisotropic in comparison with similar results for orthorhombic CaSnO{sub 3}. The complex dielectric function and the optical absorption of SrSnO{sub 3} were shown to be sensitive to the plane of polarization of the incident light. The infrared spectrum between 100 and 600 cm{sup -1} was obtained, with its main peaks being assigned, and a nice agreement between experimental and theoretical peaks of the Raman spectrum of orthorhombic SrSnO{sub 3} was achieved. -- Graphical abstract: Orthorhombic SrSnO{sub 3}: a view of the unit cell (left) and plots showing the calculated and experimental Raman spectra (right). Display Omitted Research highlights: {yields} We have performed DFT calculations on orthorhombic SrSnO{sub 3} crystals, obtaining their structural, electronical and optical properties. {yields} An indirect band gap was obtained, and anisotropic effective masses were found for both electrons and holes. {yields} The complex dielectric function and the optical absorption of SrSnO{sub 3} were shown to be very sensitive to the plane of polarization of the incident light. {yields} The infrared spectrum between 100 and 600 cm{sup -1} was obtained, with its main peaks being assigned, and a nice agreement between experimental and theoretical peaks of the Raman spectrum was achieved.
Electronvibration coupling in time-dependent density-functional theory: Application to benzene
Bertsch George F.
Electronvibration coupling in time-dependent density-functional theory: Application to benzene G://jcp.aip.org/about/rights_and_permissions #12;Electronvibration coupling in time-dependent density-functional theory: Application to benzene G for electronvibration coupling, we apply it to the optical properties of the * transitions in benzene
Klaas J. H. Giesbertz
2015-06-16T23:59:59.000Z
A theorem for the invertibility of arbitrary response functions is presented under the following conditions: the time-dependence of the potentials should be Laplace transformable and the initial state should be a ground state, though it might be degenerate. This theorem provides a rigorous foundation for all density-functional-like theories in the time-dependent linear response regime. Especially for time-dependent one-body reduced density matrix (1RDM) functional theory this is an important step forward, since a solid foundation has currently been lacking. The theorem is equally valid for static response functions in the non-degenerate case, so can be used to characterize the uniqueness of the potential in the ground state version of the corresponding density-functional-like theory. Such a classification of the uniqueness of the non-local potential in ground state 1RDM functional theory has been lacking for decades. With the aid of presented invertibility theorem presented here, a complete classification of the non-uniqueness of the non-local potential in 1RDM functional theory can be given for the first time.
Inelastic neutron scattering, Raman and DFT investigations of...
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Inelastic neutron scattering, Raman and DFT investigations of the adsorption of phenanthrenequinone on onion-like carbon Daniela M. Anjos a , Alexander I. Kolesnikov a , Zili Wu a...
Jeff Schulte; Patrick Kreitzberg; Chris Haglund; David Roundy
2012-08-31T23:59:59.000Z
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.
A proximal gradient method for ensemble density functional theory
Michael Ulbrich
2015-04-23T23:59:59.000Z
Apr 23, 2015 ... Although the widely used self-consistent field iteration method can be extended to solve the minimization of the total energy functional with ...
Ahlfors' contribution to the theory of meromorphic functions
2009-10-23T23:59:59.000Z
Oct 23, 2009 ... Notes Lvov State University, 38, 7 (1956), 53-74 (Russian). [33] A. A. Goldberg, I. V. Ostrovski, Distribution of Values of Meromorphic. Functions ...
Silvestrelli, Pier Luigi
2015-01-01T23:59:59.000Z
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...
Nakata, Ayako; Tsuneda, Takao; Hirao, Kimihiko [Advanced Science Institute, RIKEN, Wako 351-0198 (Japan); CREST, Japan Science and Technology Agency, Kawaguchi 332-0012 (Japan)
2011-12-14T23:59:59.000Z
A long-range corrected (LC) time-dependent density functional theory (TDDFT) incorporating relativistic effects with spin-orbit couplings is presented. The relativistic effects are based on the two-component zeroth-order regular approximation Hamiltonian. Before calculating the electronic excitations, we calculated the ionization potentials (IPs) of alkaline metal, alkaline-earth metal, group 12 transition metal, and rare gas atoms as the minus orbital (spinor) energies on the basis of Koopmans' theorem. We found that both long-range exchange and spin-orbit coupling effects are required to obtain Koopmans' IPs, i.e., the orbital (spinor) energies, quantitatively in DFT calculations even for first-row transition metals and systems containing large short-range exchange effects. We then calculated the valence excitations of group 12 transition metal atoms and the Rydberg excitations of rare gas atoms using spin-orbit relativistic LC-TDDFT. We found that the long-range exchange and spin-orbit coupling effects significantly contribute to the electronic spectra of even light atoms if the atoms have low-lying excitations between orbital spinors of quite different electron distributions.
Magnetic and antimagnetic rotation in covariant density functional theory
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
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.
Improving the orbital-free density functional theory description of covalent materials
Carter, Emily A.
, Los Angele, Los Angeles, California 90095-1569 and Department of Mechanical and Aerospace Engineering-free-electron-like metals such as Al and its alloys, OF-DFT employing the WGC KEDF produces bulk properties in good
Gross, E.K.U.
Transition Metals Scherz, Gross, Appel, Sorg, K. Baberschke, and Wende Fachbereich Physik, Freie UniversitaÂKohn approximation probÂ lem shown, new approximation suggested. But the value DFT constructing approxiÂ mation
Element orbitals for Kohn-Sham density functional theory
Lin, Lin; Ying, Lexing
2012-05-08T23:59:59.000Z
We present a method to discretize the Kohn-Sham Hamiltonian matrix in the pseudopotential framework by a small set of basis functions automatically contracted from a uniform basis set such as planewaves. Each basis function is localized around an element, which is a small part of the global domain containing multiple atoms. We demonstrate that the resulting basis set achieves meV accuracy for 3D densely packed systems with a small number of basis functions per atom. The procedure is applicable to insulating and metallic systems.
Exact beta-functions in softly-broken N=2 Chern-Simons matter theories
I. Jack; C. Luckhurst
2011-01-21T23:59:59.000Z
We present exact results for the beta-functions for the soft-breaking parameters in softly-broken N=2 Chern-Simons matter theories in terms of the anomalous dimension in the unbroken theory. We check our results explicitly up to the two loop level.
Green function identities in Euclidean quantum field theory
G. Sardanashvily
2006-04-01T23:59:59.000Z
Given a generic Lagrangian system of even and odd fields, we show that any infinitesimal transformation of its classical Lagrangian yields the identities which Euclidean Green functions of quantum fields satisfy.
Dynamical Wave Function Collapse Models in Quantum Measure Theory
Fay Dowker; Yousef Ghazi-Tabatabai
2008-05-15T23:59:59.000Z
The structure of Collapse Models is investigated in the framework of Quantum Measure Theory, a histories-based approach to quantum mechanics. The underlying structure of coupled classical and quantum systems is elucidated in this approach which puts both systems on a spacetime footing. The nature of the coupling is exposed: the classical histories have no dynamics of their own but are simply tied, more or less closely, to the quantum histories.
Partition Functions of Superconformal Chern-Simons Theories from Fermi Gas Approach
Sanefumi Moriyama; Tomoki Nosaka
2014-08-14T23:59:59.000Z
We study the partition function of three-dimensional ${\\mathcal N}=4$ superconformal Chern-Simons theories of the circular quiver type, which are natural generalizations of the ABJM theory, the worldvolume theory of M2-branes. In the ABJM case, it was known that the perturbative part of the partition function sums up to the Airy function as $Z(N)=e^{A}C^{-1/3}\\mathrm{Ai}[C^{-1/3}(N-B)]$ with coefficients $C$, $B$ and $A$ and that for the non-perturbative part the divergences coming from the coefficients of worldsheet instantons and membrane instantons cancel among themselves. We find that many of the interesting properties in the ABJM theory are extended to the general superconformal Chern-Simons theories. Especially, we find an explicit expression of $B$ for general ${\\mathcal N}=4$ theories, a conjectural form of $A$ for a special class of theories, and cancellation in the non-perturbative coefficients for the simplest theory next to the ABJM theory.
A Theory of Linear Fractional Transformations of Rational Functions
Reiter, Harold
functions, we say that g g if g = ax+b cx+d -1 g ax+b cx+d , where a b c d = 0. For practical purposes ax+b cx+d = ax + b, a linear function, our methods yield a large number of first level invariants and n i=0 Aixi and n i=0 Bixi have no roots in common. Also, g g if g = ax+b cx+d -1 g ax+b cx
Smoothness of the Gap Function in the BCS-Bogoliubov Theory of Superconductivity
Shuji Watanabe
2010-06-07T23:59:59.000Z
We deal with the gap equation in the BCS-Bogoliubov theory of superconductivity, where the gap function is a function of the temperature $T$ only. We show that the squared gap function is of class $C^2$ on the closed interval $[\\,0,\\,T_c\\,]$. Here, $T_c$ stands for the transition temperature. Furthermore, we show that the gap function is monotonically decreasing on $[0,\\,T_c]$ and obtain the behavior of the gap function at $T=T_c$. We mathematically point out some more properties of the gap function.
Nonequilibrium thermodynamics of interfaces using classical density functional theory
Kjelstrup, Signe
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
Bryan M. Wong; Joseph G. Cordaro
2011-09-15T23:59:59.000Z
The band structure and electronic properties in a series of vinylene-linked heterocyclic conducting polymers are investigated using density functional theory (DFT). In order to accurately calculate electronic band gaps, we utilize hybrid functionals with fully periodic boundary conditions to understand the effect of chemical functionalization on the electronic structure of these materials. The use of predictive first-principles calculations coupled with simple chemical arguments highlights the critical role that aromaticity plays in obtaining a low band gap polymer. Contrary to some approaches which erroneously attempt to lower the band gap by increasing the aromaticity of the polymer backbone, we show that being aromatic (or quinoidal) in itself does not insure a low band gap. Rather, an iterative approach which destabilizes the ground state of the parent polymer towards the aromatic \\leftrightarrow quinoidal level-crossing on the potential energy surface is a more effective way of lowering the band gap in these conjugated systems. Our results highlight the use of predictive calculations guided by rational chemical intuition for designing low band gap polymers in photovoltaic materials.
Boccia, A.; Lanzilotto, V.; Marrani, A. G.; Zanoni, R. [Dipartimento di Chimica, Universita degli Studi di Roma ''La Sapienza'', piazzale Aldo Moro 5, I-00185 Rome (Italy); Stranges, S. [Dipartimento di Chimica, Universita degli Studi di Roma ''La Sapienza'', piazzale Aldo Moro 5, I-00185 Rome (Italy); IOM-CNR, Laboratorio TASC, I-34149 Basovizza, Trieste (Italy); Alagia, M. [IOM-CNR, Laboratorio TASC, I-34149 Basovizza, Trieste (Italy); Fronzoni, G.; Decleva, P. [Dipartimento di Scienze Chimiche, Universita di Trieste, Via L. Giorgieri 1, I-34127 Trieste, Italy and IOM-CNR Democritos, Trieste (Italy)
2012-04-07T23:59:59.000Z
We present the results of an experimental and theoretical investigation of monosubstituted ethyl-, vinyl-, and ethynyl-ferrocene (EtFC, VFC, and EFC) free molecules, obtained by means of synchrotron-radiation based C 1s photoabsorption (NEXAFS) and photoemission (C 1s XPS) spectroscopies, and density functional theory (DFT) calculations. Such a combined study is aimed at elucidating the role played by the C-C bond unsaturation degree of the substituent on the electronic structure of the ferrocene derivatives. Such substituents are required for molecular chemical anchoring onto relevant surfaces when ferrocenes are used for molecular electronics hybrid devices. The high resolution C 1s NEXAFS spectra exhibit distinctive features that depend on the degree of unsaturation of the hydrocarbon substituent. The theoretical approach to consider the NEXAFS spectrum made of three parts allowed to disentangle the specific contribution of the substituent group to the experimental spectrum as a function of its unsaturation degree. C 1s IEs were derived from the experimental data analysis based on the DFT calculated IE values for the different carbon atoms of the substituent and cyclopentadienyl (Cp) rings. Distinctive trends of chemical shifts were observed for the substituent carbon atoms and the substituted atom of the Cp ring along the series of ferrocenes. The calculated IE pattern was rationalized in terms of initial and final state effects influencing the IE value, with special regard to the different mechanism of electron conjugation between the Cp ring and the substituent, namely the {sigma}/{pi} hyperconjugation in EtFC and the {pi}-conjugation in VFC and EFC.
Function group approach to unconstrained Hamiltonian Yang-Mills theory
Antti Salmela
2005-09-07T23:59:59.000Z
Starting from the temporal gauge Hamiltonian for classical pure Yang-Mills theory with the gauge group SU(2) a canonical transformation is initiated by parametrising the Gauss law generators with three new canonical variables. The construction of the remaining variables of the new set proceeds through a number of intermediate variables in several steps, which are suggested by the Poisson bracket relations and the gauge transformation properties of these variables. The unconstrained Hamiltonian is obtained from the original one by expressing it in the new variables and then setting the Gauss law generators to zero. This Hamiltonian turns out to be local and it decomposes into a finite Laurent series in powers of the coupling constant.
The Gaussian Radial Basis Function Method for Plasma Kinetic Theory
Hirvijoki, Eero; Belli, Emily; Embréus, Ola
2015-01-01T23:59:59.000Z
A fundamental macroscopic description of a magnetized plasma is the Vlasov equation supplemented by the nonlinear inverse-square force Fokker-Planck collision operator [Rosenbluth et al., Phys. Rev., 107, 1957]. The Vlasov part describes advection in a six-dimensional phase space whereas the collision operator involves friction and diffusion coefficients that are weighted velocity-space integrals of the particle distribution function. The Fokker-Planck collision operator is an integro-differential, bilinear operator, and numerical discretization of the operator is far from trivial. In this letter, we describe a new approach to discretize the entire kinetic system based on an expansion in Gaussian Radial Basis functions (RBFs). This approach is particularly well-suited to treat the collision operator because the friction and diffusion coefficients can be analytically calculated. Although the RBF method is known to be a powerful scheme for the interpolation of scattered multidimensional data, Gaussian RBFs also...
Molecular Density Functional Theory for water with liquid-gas coexistence and correct pressure
Jeanmairet, Guillaume; Sergiievskyi, Volodymyr; Borgis, Daniel
2015-01-01T23:59:59.000Z
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...
Gautam, P.; Gautam, D.; Chaudhary, R. P., E-mail: rpchaudhary65@gmail.com [Sant Longowal Institute of Engineering and Technology, Department of Chemistry (India)
2013-12-15T23:59:59.000Z
The title compound N-(4-acetyl-5,5-dimethyl-4,5-dihydro-1,3,4-thiadiazol-2-yl)acetamide (III) was obtained from the reaction of 2-(propan-2-ylidene)hydrazinecarbothioamide (II) with acetic anhydride instead of formation of the desired thiosemcarbazide derivative of Meldrum acid. The structures of II and III were established by elemental analysis, IR, NMR, Mass and X-ray crystallographic studies. II crystallizes in triclinic system, sp. gr. P-bar1 Z = 2; III crystallizes in the monoclinic system, sp. gr. P2{sub 1}/c, Z = 8. Density functional theory (DFT) calculations have been carried out for III. {sup 1}H and {sup 13}C NMR of III has been calculated and correlated with experimental results.
Note on potential theory for functions in Hardy classes
Truong, Tuyen Trung
2008-01-01T23:59:59.000Z
The purpose of this note is to show that the set functions defined in \\cite{trong-tuyen} can be suitably extended to all subsets $E$ of the unit disk $\\mathbb{D}$. In particular we obtain uniform nearly-optimal estimates for the following quantity D_p(E,\\epsilon, R) = \\sup \\{\\sup_{|z| \\leq R}|g(z)|: g\\in H^p, ||g||_{H^p}\\leq 1, (1-|\\zeta |)|g(\\zeta)| \\leq \\epsilon \\forall \\zeta\\in E\\}.
Simple regularization scheme for multi-reference density functional theories
Wojciech Satula; Jacek Dobaczewski
2014-07-03T23:59:59.000Z
Background: Extensions of single-reference (SR) energy-density-functionals (EDFs) to multi-reference (MR) applications involve using the generalized Wick theorem (GWT), which leads to singular energy kernels that cannot be properly integrated to restore symmetries, unless the EDFs are generated by true interactions. Purpose: We propose a new method to regularize the MR EDFs, which is based on using auxiliary quantities obtained by multiplying the kernels with appropriate powers of overlaps. Methods: Regularized matrix elements of two-body interactions are obtained by integrating the auxiliary quantities and then solving simple linear equations. Results: We implement the new regularization method within the self-consistent Skyrme-Hartree-Fock approach and we perform a proof-of-principle angular-momentum projection (AMP) of states in odd-odd nucleus 26Al. We show that for EDFs generated by true interactions, our regularization method gives results identical to those obtained within the standard AMP procedure. We also show that for EDFs that do not correspond to true interactions, it gives stable and converging results that are different than unstable and non-converging standard AMP values. Conclusions: The new regularization method proposed in this work may provide us with a relatively inexpensive and efficient tool to generalize SR EDFs to MR applications, thus allowing for symmetry restoration and configuration mixing performed for typical nuclear EDFs, which most often do not correspond to true interactions.
Sit, P H L.; Cococcioni, Matteo; Marzari, Nicola N.
2007-09-01T23:59:59.000Z
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. We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car–Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT + U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexaaqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe–O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe–O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.
P. H. -L. Sit; Matteo Cococcioni; Nicola Marzari
2007-01-12T23:59:59.000Z
We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car-Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT+U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexa-aqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe-O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe-O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.
Session #1: Cutting Edge Methodologies--Beyond Current DFT
Broader source: Energy.gov (indexed) [DOE]
dimer PBE LDA Exp CCSD(T) LDA PBE vdW Interaction between H 2 and Carbon PBE Graphene CCSD(T) LDA Benzene omitted in the LDA and GGA van der Walls (vdW)-DFT: Langreth,...
New Development of Self-Interaction Corrected DFT for Extended...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
DFT-SIC calculation can be carried out efficiently even for extended systems. Using this new development the formation energies of defects in 3C-SiC were calculated and compared...
Telnov, Dmitry A.; Chu, Shih-I
2000-12-13T23:59:59.000Z
In the framework of the Floquet formulation of time-dependent density functional theory we present several exact relations involving different parts of the quasienergy functional. These relations hold when the exact densities ...
Photon wave functions, wave-packet quantization of light, and coherence theory
Brian J. Smith; M. G. Raymer
2007-12-09T23:59:59.000Z
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.
Geometry of Spin and Spin^c structures in the M-theory partition function
Hisham Sati
2012-04-01T23:59:59.000Z
We study the effects of having multiple Spin structures on the partition function of the spacetime fields in M-theory. This leads to a potential anomaly which appears in the eta-invariants upon variation of the Spin structure. The main source of such spaces are manifolds with nontrivial fundamental group, which are also important in realistic models. We extend the discussion to the Spin^c case and find the phase of the partition function, and revisit the quantization condition for the C-field in this case. In type IIA string theory in ten dimensions, the mod 2 index of the Dirac operator is the obstruction to having a well-defined partition function. We geometrically characterize manifolds with and without such an anomaly and extend to the case of nontrivial fundamental group. The lift to KO-theory gives the alpha-invariant, which in general depends on the Spin structure. This reveals many interesting connection to positive scalar curvature manifolds and constructions related to the Gromov-Lawson-Rosenberg conjecture. In the twelve-dimensional theory bounding M-theory, we study similar geometric questions, including choices of metrics and obtaining elements of K-theory in ten dimensions by pushforward in K-theory on the disk fiber. We interpret the latter in terms of the families index theorem for Dirac operators on the M-theory circle and disk. This involves superconnections, eta-forms, and infinite-dimensional bundles, and gives elements in Deligne cohomology in lower dimensions. We illustrate our discussion with many examples throughout.
Four-point correlation function of stress-energy tensors in N=4 superconformal theories
Korchemsky, G P
2015-01-01T23:59:59.000Z
We derive the explicit expression for the four-point correlation function of stress-energy tensors in four-dimensional N=4 superconformal theory. We show that it has a remarkably simple and suggestive form allowing us to predict a large class of four-point correlation functions involving the stress-energy tensor and other conserved currents. We then apply the obtained results on the correlation functions to computing the energy-energy correlations, which measure the flow of energy in the final states created from the vacuum by a source. We demonstrate that they are given by a universal function independent of the choice of the source. Our analysis relies only on N=4 superconformal symmetry and does not use the dynamics of the theory.
Senjean, Bruno; Jensen, Hans Jørgen Aa; Fromager, Emmanuel
2015-01-01T23:59:59.000Z
The computation of excitation energies in range-separated ensemble density-functional theory (DFT) is discussed. The latter approach is appealing as it enables the rigorous formulation of a multi-determinant state-averaged DFT method. In the exact theory, the short-range density functional, that complements the long-range wavefunction-based ensemble energy contribution, should vary with the ensemble weights even when the density is held fixed. This weight dependence ensures that the range-separated ensemble energy varies linearly with the ensemble weights. When the (weight-independent) ground-state short-range exchange-correlation functional is used in this context, curvature appears thus leading to an approximate weight-dependent excitation energy. In order to obtain unambiguous approximate excitation energies, we simply propose to interpolate linearly the ensemble energy between equiensembles. It is shown that such a linear interpolation method (LIM) effectively introduces weight dependence effects. LIM has...
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
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), UV–vis–NIR 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 N–Ni interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.
Qian Zhao; Bao Yuan Sun; Wen Hui Long
2014-11-23T23:59:59.000Z
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.
Relative stability of nanosized wurtzite and graphitic ZnO from density functional theory
Melnik, Roderick
Relative stability of nanosized wurtzite and graphitic ZnO from density functional theory Bin Wen to determine the relative stability of wurtzite and graphitic phases of ZnO nanostructures. Our results the threshold number, the relative stability of the wurtzite phase is observed. Finally, we discuss
A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder*
Ceder, Gerbrand
. The effect of the framework on the physical structure and electronic structure of the organic linker initio molecular dynamics in the generalized gradient approximation to density functional theory, and calculations indicate that the sites with the strongest interaction with hydrogen are located near the Zn4O
Electronvibration coupling in time-dependent density-functional theory: Application to benzene
Bertsch George F.
Electronvibration coupling in time-dependent density-functional theory: Application to benzene G for electronvibration coupling, we apply it to the optical properties of the * transitions in benzene with the electronic excitations. In this work, we have chosen the benzene model for an exploratory study
Szállás, 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); Szász, 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, Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary); Trinh, X. T.; Son, N. T.; Janzén, E. [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (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 út 8, H-1111 Budapest (Hungary)
2014-09-21T23:59:59.000Z
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.
Relativistic density functional theory modeling of plutonium and americium higher oxide molecules
Titov, Anatoly
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
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), Linköping University, SE-58183 Linköping (Sweden)] [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden)
2014-05-14T23:59:59.000Z
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 Cu–O 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.
Gunceler, Deniz; Sundararaman, Ravishankar; Schwarz, Kathleen A; Arias, T A
2013-01-01T23:59:59.000Z
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...
Correlation functions of the energy-momentum tensor in SU(2) gauge theory at finite temperature
Huebner, K; Pica, C
2008-01-01T23:59:59.000Z
We calculate correlation functions of the energy-momentum tensor in the vicinity of the deconfinement phase transition of (3+1)-dimensional SU(2) gauge theory and discuss their critical behavior in the vicinity of the second order deconfinement transition. We show that correlation functions of the trace of the energy momentum tensor diverge uniformly at the critical point in proportion to the specific heat singularity. Correlation functions of the pressure, on the other hand, stay finite at the critical point. We discuss the consequences of these findings for the analysis of transport coefficients, in particular the bulk viscosity, in the vicinity of a second order phase transition point.
Chu, Shih-I; Tong, Xiao-Min
1998-02-01T23:59:59.000Z
to the relativistic regime also has been con- sidered @6,7#. However, with the exception of a recent rela- tivistic local-density-functional calculation @8#, there is no systematic relativistic DFT studies of atomic ground-state properties across the Periodic Table...-interaction energy @1#. A similar problem exists for the relativistic xc energy functionals @6,7#. For a quantitative treatment of photoionization or multipho- ton ionization processes, it is necessary that both the ioniza- tion potential and the excited...
Boyer, Edmond
case in which coupled cluster theory is used to obtain the density and excitation energies for benchmark and highly accurate studies, they are still too demanding for standard applications. Another
R. Rodriguez-Guzman; Y. Alhassid; G. F. Bertsch
2007-09-04T23:59:59.000Z
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.
Carter, Emily A.
2012-01-01T23:59:59.000Z
, Princeton, New Jersey 08544, USA Emily A. Carter Departments of Mechanical and Aerospace Engineering. However, OF-DFT Ag-Al alloy properties differ substantially from those predicted by KS-DFT using nonlocal is that when the system contains many different elements, such as in complex metal alloys, it becomes difficult
Gold-plated moments of nucleon structure functions in baryon chiral perturbation theory
Vadim Lensky; Jose Manuel Alarcón; Vladimir Pascalutsa
2014-11-09T23:59:59.000Z
We obtain leading- and next-to-leading order predictions of chiral perturbation theory for several prominent moments of nucleon structure functions. These free-parameter free results turn out to be in overall agreement with the available empirical information on nearly all of the considered moments, in the region of low-momentum transfer ($Q^2 < 0.3$ GeV$^2$). Especially surprising is the situation for the spin polarizability $\\delta_{LT}$, which thus far was not reproducible in chiral perturbation theory for proton and neutron simultaneously. This problem, known as the "$\\delta_{LT}$ puzzle," is not seen in the present calculation.
Infrared Behavior of 3-Point Functions in Landau Gauge Yang-Mills Theory
Markus Q. Huber; Reinhard Alkofer; Kai Schwenzer
2008-12-23T23:59:59.000Z
The three-gluon and ghost-gluon vertices of Landau gauge Yang-Mills theory are investigated in the low momentum regime. Due to ghost dominance in the infrared we can use the known power law behavior for the propagators to determine analytically the complete momentum dependence of the dressing functions. Besides a uniform, i. e. all momenta going to zero, divergence, we find additional singularities, if one momentum alone goes to zero, while the other two remain constant. At these asymmetric points we can extract additional infrared exponents, which corroborate previous results and expand the known fixed point solution of Landau gauge Yang-Mills theory, where the uniform infrared exponents for all vertex functions are known. Calculations in two and three dimensions yield qualitatively similar results.
The three-loop beta function in SU(N) lattice gauge theories
B. Alles; A. Feo; H. Panagopoulos
1996-09-11T23:59:59.000Z
We calculate the third coefficient of the lattice $\\beta$ function in pure Yang-Mills theory. We make use of a computer code for solving perturbation theory analytically on the lattice. We compute the divergent integrals by using a method based on a Taylor expansion of the integrand in powers of the external momenta in $4 - \\epsilon$ dimensions. Our results are in agreement with a previous calculation by M. L\\"uscher and P. Weisz where the authors used a different technique. We also show how this new coefficient modifies the scaling function on the lattice in both the standard and energy schemes. In particular we show that asymptotic scaling is extremely well achieved in the energy scheme.
Computationally efficient double hybrid density functional theory using dual basis methods
Byrd, Jason N
2015-01-01T23:59:59.000Z
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.
Covariant density functional theory with two-phonon coupling in nuclei
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
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.
Steam Reforming on Transition-metal Carbides from Density-functional Theory
Vojvodic, Aleksandra
2012-05-11T23:59:59.000Z
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.
Building A Universal Nuclear Energy Density Functional (UNEDF)
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
During the period of Dec. 1 2006 â?? 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.
Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles
Angioletti-Uberti, Stefano; Dzubiella, Joachim
2014-01-01T23:59:59.000Z
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 th...
Large-order perturbation theory for the electromagnetic current-current correlation function
Brown, L.S.; Yaffe, L.G.; Zhai, C. (Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States))
1992-11-15T23:59:59.000Z
The constraints imposed by asymptotic freedom and analyticity on the large-order behavior of perturbation theory for the electromagnetic current-current correlation function are examined. By suitably applying the renormalization group, the coefficients of the asymptotic expansion in the deep Euclidean region may be expressed explicitly in terms of the perturbative coefficients of the Minkowski space discontinuity (the {ital R} ratio in {ital e}{sup +}{ital e{minus}} scattering). This relation yields a generic'' prediction for the large-order behavior of the Euclidean perturbation series and suggests the presence of nonperturbative 1/{ital q}{sup 2} correction in the Euclidean correlation function. No such generic'' prediction can be made for the physically measurable {ital R} ratio. A novel functional method is developed to obtain these results.
Davis, A. B. (Anthony B.); Marshak, A. (Alexander); Cahalan, R. F. (Robert F.)
2001-01-01T23:59:59.000Z
We survey radiative Green function theory (1) in linear transport theory where numerical procedures are required to obtain specific results and (2) in the photon diffusion limit (large optical depths) where it is analytically tractable, at least for homogeneous plane-parallel media. We then describe two recent applications of Green function theory to passive cloud remote sensing in the presence of strong three-dimensional transport effects. Finally, we describe recent instrumental breakthroughs in 'off-beam' cloud lidar which is based on direct measurements of radiative Green functions with special attention to the data collected during the Shuttle-based Lidar In-space Technology Experiment (LITE) mission.
Band gap corrections for molecules and solids using Koopmans theorem and Wannier functions
Ma, Jie
2015-01-01T23:59:59.000Z
We have proposed a method for correcting the Kohn-Sham eigen energies in the density functional theory (DFT) based on the Koopmans theorem using Wannier functions. The method provides a general approach applicable for molecules and solids for electronic structure calculations. It does not have any adjustable parameters and the computational cost is at the DFT level. For solids, the calculated eigen energies agree well with the experiments for not only the band gaps, but also the energies of other valence and conduction bands. For molecules, the calculated eigen energies agree well with the experimental ionization potentials and electron affinities, and show better trends than the traditional Delta-self-consistent-field (?SCF) results.
Qiang Zhao; Jian Min Dong; Jun Ling Song; Wen Hui Long
2014-07-23T23:59:59.000Z
Half-life of proton radioactivity of spherical proton emitters is studied within the scheme of covariant density functional (CDF) theory, and for the first time the potential barrier that prevents the emitted proton is extracted with the similarity renormalization group (SRG) method, in which the spin-orbit potential along with the others that turn out to be non-negligible can be derived automatically. The spectroscopic factor that is significant is also extracted from the CDF calculations. The estimated half-lives are found in good agreement with the experimental values, which not only confirms the validity of the CDF theory in describing the proton-rich nuclei, but also indicates the prediction power of present approach to calculate the half-lives and in turn to extract the structural information of proton emitters.
Analytic cubic and quartic force fields using density-functional theory
Ringholm, Magnus; Gao, Bin; Thorvaldsen, Andreas J.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø—The Arctic University of Norway, 9037 Tromsø (Norway)] [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø—The Arctic University of Norway, 9037 Tromsø (Norway); Jonsson, Dan [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø—The Arctic University of Norway, 9037 Tromsø (Norway) [Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø—The Arctic University of Norway, 9037 Tromsø (Norway); High Performance Computing Group, University of Tromsø—The Arctic University of Norway, 9037 Tromsø (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); Ekström, 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
We present the first analytic implementation of cubic and quartic force constants at the level of Kohn–Sham 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 exchange–correlation kernels. We use generalized second-order vibrational perturbation theory to calculate the fundamental frequencies of methane, ethane, benzene, and aniline, comparing B3LYP, BLYP, and Hartree–Fock results. The Hartree–Fock 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.
Firoozabadi, Abbas
representa- tion of various intermolecular interactions e.g., short-range repulsions, van der Waals- ing of hydrocarbons, N2, CO2, H2S, and sometimes water, DFT at the current stage only exhibits very
Cornaton, Yann; Jensen, Hans Jørgen Aa; Fromager, Emmanuel
2013-01-01T23:59:59.000Z
An alternative separation of short-range exchange and correlation energies is used in the framework of second-order range-separated density-functional perturbation theory. This alternative separation was initially proposed by Toulouse et al. [Theor. Chem. Acc. 114, 305 (2005)] and relies on a long-range interacting wavefunction instead of the non-interacting Kohn-Sham one. When second-order corrections to the density are neglected, the energy expression reduces to a range-separated double-hybrid (RSDH) type of functional, RSDHf, where "f" stands for "full-range integrals" as the regular full-range interaction appears explicitly in the energy expression when expanded in perturbation theory. In contrast to usual RSDH functionals, RSDHf describes the coupling between long- and short-range correlations as an orbital-dependent contribution. Calculations on the first four noble-gas dimers show that this coupling has a significant effect on the potential energy curves in the equilibrium region, improving the accurac...
Correlation of Theory and Function in Well-Defined Bimetallic Electrocatalysts - Final Report
Crooks, Richard M.
2014-06-05T23:59:59.000Z
The objective of this research proposal was to correlate the structure of nanoparticles that are comprised of ~100-200 atoms to their electrocatalytic function. This objective was based on the growing body of evidence suggesting that catalytic properties can be tailored through controlled synthesis of nanoparticles. What has been missing from many of these studies, and what we are contributing, is a model catalyst that is sufficiently small, structurally well-defined, and well-characterized that its function can be directly predicted by theory. Specifically, our work seeks to develop a fundamental and detailed understanding of the relationship between the structure of nanoscopic oxygen-reduction catalysts and their function. We assembled a team with expertise in theory, synthesis, and advanced characterization methods to address the primary objective of this project. We anticipated the outcomes of the study to be: (1) a better theoretical understanding of how nanoparticle structure affects catalytic properties; (2) the development of advanced, in-situ and ex-situ, atomic-scale characterization methods that are appropriate for particles containing about 100 atoms; and (3) improved synthetic methods that produce unique nanoparticle structures that can be used to test theoretical predictions. During the project period, we have made excellent progress on all three fronts.
Free-energy functional of the electronic potential for Schrödinger-Poisson theory
Vikram Jadhao; Kaushik Mitra; Francisco J. Solis; Monica Olvera de la Cruz
2014-12-15T23:59:59.000Z
In the study of model electronic device systems where electrons are typically under confinement, a key obstacle is the need to iteratively solve the coupled Schr\\"{o}dinger-Poisson (SP) equation. It is possible to bypass this obstacle by adopting a variational approach and obtaining the solution of the SP equation by minimizing a functional. Further, using molecular dynamics methods that treat the electronic potential as a dynamical variable, the functional can be minimized on the fly in conjunction with the update of other dynamical degrees of freedom leading to considerable reduction in computational costs. But such approaches require access to a true free-energy functional, one that evaluates to the equilibrium free energy at its minimum. In this paper, we present a variational formulation of the Schr\\"{o}dinger-Poisson (SP) theory with the needed free-energy functional of the electronic potential. We apply our formulation to semiconducting nanostructures and provide the expression of the free-energy functional for narrow channel quantum wells where the local density approximation yields accurate physics and for the case of wider channels where Thomas-Fermi approximation is valid.
Song, Xueyu
online 18 July 2008 Free energies and correlation functions of liquid and solid hard-sphere HS mixtures theory the free energies of solid and liquid Lennard-Jones LJ mixtures are obtained from correlation, Chandler, and Andersen WCA Refs. 5 and 6 perturbation theory, the free energy is separated into two parts
Orbital-free density functional theory of out-of-plane charge screening in graphene
Jianfeng Lu; Vitaly Moroz; Cyrill B. Muratov
2015-06-30T23:59:59.000Z
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 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.
Orbital-free density functional theory of out-of-plane charge screening in graphene
Jianfeng Lu; Vitaly Moroz; Cyrill B. Muratov
2014-05-20T23:59:59.000Z
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.
Quasi-particle energy spectra in local reduced density matrix functional theory
Lathiotakis, Nektarios N. [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Vass. Constantinou 48, GR-11635 Athens (Greece); Helbig, Nicole [Peter-Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich, D-52425 Jülich (Germany); Rubio, Angel [Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Dpto. Física de Materiales, Universidad del País Vasco, CFM CSIC-UPV/EHU-MPC and DIPC, Av. Tolosa 72, E-20018 San Sebastián (Spain); Gidopoulos, Nikitas I. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
2014-10-28T23:59:59.000Z
Recently, we introduced [N. N. Lathiotakis, N. Helbig, A. Rubio, and N. I. Gidopoulos, Phys. Rev. A 90, 032511 (2014)] local reduced density matrix functional theory (local RDMFT), a theoretical scheme capable of incorporating static correlation effects in Kohn-Sham equations. Here, we apply local RDMFT to molecular systems of relatively large size, as a demonstration of its computational efficiency and its accuracy in predicting single-electron properties from the eigenvalue spectrum of the single-particle Hamiltonian with a local effective potential. We present encouraging results on the photoelectron spectrum of molecular systems and the relative stability of C{sub 20} isotopes. In addition, we propose a modelling of the fractional occupancies as functions of the orbital energies that further improves the efficiency of the method useful in applications to large systems and solids.
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
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.
Sussman, Joel L.
Theoretical Insight into the Interactions of TMA-Benzene and TMA-Pyrrole with B3LYP Density theoretical investigation of the tetramethylammonium(TMA)-benzene and TMA-pyrrole complexes has been performed density in the 5 6 aromatic system of pyrrole is larger than that in the 6 6 system of benzene
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power Administration wouldDECOMPOSITIONPortalTo help ensure that sulfatesDoLaboratory
J. D. McDonnell; N. Schunck; D. Higdon; J. Sarich; S. M. Wild; W. Nazarewicz
2015-01-15T23:59:59.000Z
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.
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
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.
Hydration of gas-phase ytterbium ion complexes studied by experiment and theory
Rutkowski, Philip X; Michelini, Maria C.; Bray, Travis H.; Russo, Nino; Marcalo, Joaquim; Gibson, John K.
2011-02-11T23:59:59.000Z
Hydration of ytterbium (III) halide/hydroxide ions produced by electrospray ionization was studied in a quadrupole ion trap mass spectrometer and by density functional theory (DFT). Gas-phase YbX{sub 2}{sup +} and YbX(OH){sup +} (X = OH, Cl, Br, or I) were found to coordinate from one to four water molecules, depending on the ion residence time in the trap. From the time dependence of the hydration steps, relative reaction rates were obtained. It was determined that the second hydration was faster than both the first and third hydrations, and the fourth hydration was the slowest; this ordering reflects a combination of insufficient degrees of freedom for cooling the hot monohydrate ion and decreasing binding energies with increasing hydration number. Hydration energetics and hydrate structures were computed using two approaches of DFT. The relativistic scalar ZORA approach was used with the PBE functional and all-electron TZ2P basis sets; the B3LYP functional was used with the Stuttgart relativistic small-core ANO/ECP basis sets. The parallel experimental and computational results illuminate fundamental aspects of hydration of f-element ion complexes. The experimental observations - kinetics and extent of hydration - are discussed in relationship to the computed structures and energetics of the hydrates. The absence of pentahydrates is in accord with the DFT results, which indicate that the lowest energy structures have the fifth water molecule in the second shell.
Vijayakumar, M.; Hu, Jian Z.
2013-10-15T23:59:59.000Z
To analyze the lithium ion interaction with realistic graphene surfaces, we carried out dispersion corrected DFT-D3 studies on graphene with common point defects and chemisorbed oxygen containing functional groups along with defect free graphene surface. Our study reveals that, the interaction between lithium ion (Li+) and graphene is mainly through the delocalized ? electron of pure graphene layer. However, the oxygen containing functional groups pose high adsorption energy for lithium ion due to the Li-O ionic bond formation. Similarly, the point defect groups interact with lithium ion through possible carbon dangling bonds and/or cation-? type interactions. Overall these defect sites render a preferential site for lithium ions compared with pure graphene layer. Based on these findings, the role of graphene surface defects in lithium battery performance were discussed.
Alavi, Ali
Coupled cluster benchmarks of water monomers and dimers extracted from density-functional theory functionals in simulations of liquid water, water monomers and dimers were extracted from a PBE simulation liquid water: The importance of monomer deformations Biswajit Santra,1 Angelos Michaelides,1,2,a
Complex-energy approach to sum rules within nuclear density functional theory
Nobuo Hinohara; Markus Kortelainen; Witold Nazarewicz; Erik Olsen
2015-01-28T23:59:59.000Z
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.
Cahoon, James B.; Kling, Matthias F.; Sawyer, Karma R.; Andersen, Lars K.; Harris, Charles B.
2008-04-30T23:59:59.000Z
The photochemical disproportionation mechanism of [CpW(CO){sub 3}]{sub 2} in the presence of Lewis bases PR{sub 3} was investigated on the nano- and microsecond time-scales with Step-Scan FTIR time-resolved infrared spectroscopy. 532 nm laser excitation was used to homolytically cleave the W-W bond, forming the 17-electron radicals CpW(CO){sub 3} and initiating the reaction. With the Lewis base PPh{sub 3}, disproportionation to form the ionic products CpW(CO){sub 3}PPh{sub 3}{sup +} and CpW(CO){sub 3}{sup -} was directly monitored on the microsecond time-scale. Detailed examination of the kinetics and concentration dependence of this reaction indicates that disproportionation proceeds by electron transfer from the 19-electron species CpW(CO){sub 3}PPh{sub 3} to the 17-electron species CpW(CO){sub 3}. This result is contrary to the currently accepted disproportionation mechanism which predicts electron transfer from the 19-electron species to the dimer [CpW(CO){sub 3}]{sub 2}. With the Lewis base P(OMe){sub 3} on the other hand, ligand substitution to form the product [CpW(CO){sub 2}P(OMe){sub 3}]{sub 2} is the primary reaction on the microsecond time-scale. Density Functional Theory (DFT) calculations support the experimental results and suggest that the differences in the reactivity between P(OMe){sub 3} and PPh{sub 3} are due to steric effects. The results indicate that radical-to-radical electron transfer is a previously unknown but important process for the formation of ionic products with the organometallic dimer [CpW(CO){sub 3}]{sub 2} and may also be applicable to the entire class of organometallic dimers containing a single metal-metal bond.
Prediction of Iron K-Edge Absorption Spectra Using Time-Dependent Density Functional Theory
George, S.DeBeer; Petrenko, T.; Neese, F.
2009-05-14T23:59:59.000Z
Iron K-edge X-ray absorption pre-edge features have been calculated using a time-dependent density functional approach. The influence of functional, solvation, and relativistic effects on the calculated energies and intensities has been examined by correlation of the calculated parameters to experimental data on a series of 10 iron model complexes, which span a range of high-spin and low-spin ferrous and ferric complexes in O{sub h} to T{sub d} geometries. Both quadrupole and dipole contributions to the spectra have been calculated. We find that good agreement between theory and experiment is obtained by using the BP86 functional with the CP(PPP) basis set on the Fe and TZVP one of the remaining atoms. Inclusion of solvation yields a small improvement in the calculated energies. However, the inclusion of scalar relativistic effects did not yield any improved correlation with experiment. The use of these methods to uniquely assign individual spectral transitions and to examine experimental contributions to backbonding is discussed.
Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles
Stefano Angioletti-Uberti; Matthias Ballauff; Joachim Dzubiella
2014-07-30T23:59:59.000Z
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.
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, Università di Torino, Corso Massimo D’Azeglio 48, I-10125 Torino (Italy)] [Dipartimento di Chimica, Università di Torino, Corso Massimo D’Azeglio 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); Causà, 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, Università di Napoli “Federico II,” Via Cintia, 80126 Napoli (Italy)] [Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università 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, Università di Napoli “Federico II,” Complesso Universitario di Monte Sant’Angelo, Via Cintia, I-80126 Napoli (Italy)] [Dipartimento di Scienze Chimiche, Università di Napoli “Federico II,” Complesso Universitario di Monte Sant’Angelo, Via Cintia, I-80126 Napoli (Italy)
2013-12-28T23:59:59.000Z
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 Møller-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)
Sako, Akifumi; Suzuki, Toshiya [Department of Mathematics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Department of Physics, Faculty of Science, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan)
2006-01-15T23:59:59.000Z
We investigate cohomological gauge theories in noncommutative R{sup 2D}. We show that vacuum expectation values of the theories do not depend on noncommutative parameters, and the large noncommutative parameter limit is equivalent to the dimensional reduction. As a result of these facts, we show that a partition function of a cohomological theory defined in noncommutative R{sup 2D} and a partition function of a cohomological field theory in R{sup 2D+2} are equivalent if they are connected through dimensional reduction. Therefore, we find several partition functions of supersymmetric gauge theories in various dimensions are equivalent. Using this technique, we determine the partition function of the N=4 U(1) gauge theory in noncommutative R{sup 4}, where its action does not include a topological term. The result is common among (8-dim, N=2), (6-dim, N=2), (2-dim, N=8) and the IKKT matrix model given by their dimensional reduction to 0-dim.
Jeanmairet, Guillaume; Levesque, Maximilien; Rotenberg, Benjamin; Borgis, Daniel
2014-01-01T23:59:59.000Z
We report here how the hydration of complex surfaces can be efficiently studied thanks to recent advances in classical molecular density functional theory. This is illustrated on the example of the pyrophylite clay. After presenting the most recent advances, we show that the strength of this implicit method is that (i) it is in quantitative or semi-quantitative agreement with reference all-atoms simulations (molecular dynamics here) for both the solvation structure and energetics, and that (ii) the computational cost is two to three orders of magnitude less than in explicit methods. The method remains imperfect, in that it locally overestimates the polarization of water close to hydrophylic sites of the clay. The high numerical efficiency of the method is illustrated and exploited to carry a systematic study of the electrostatic and van der Waals components of the surface-solvant interactions within the most popular force field for clays, CLAYFF. Hydration structure and energetics are found to weakly depend u...
Green's function method for single-particle resonant states in relativistic mean field theory
T. T. Sun; S. Q. Zhang; Y. Zhang; J. N. Hu; J. Meng
2014-09-30T23:59:59.000Z
Relativistic mean field theory is formulated with the Green's function method in coordinate space to investigate the single-particle bound states and resonant states on the same footing. Taking the density of states for free particle as a reference, the energies and widths of single-particle resonant states are extracted from the density of states without any ambiguity. As an example, the energies and widths for single-neutron resonant states in $^{120}$Sn are compared with those obtained by the scattering phase-shift method, the analytic continuation in the coupling constant approach, the real stabilization method and the complex scaling method. Excellent agreements are found for the energies and widths of single-neutron resonant states.
Mussard, Bastien; Ángyán, János G
2015-01-01T23:59:59.000Z
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.
Yao, J M; Hagino, K; Ring, P; Meng, J
2014-01-01T23:59:59.000Z
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.
Steam reforming on transition-metal carbides from density-functional theory
Vojvodic, Aleksandra
2009-01-01T23:59:59.000Z
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.
Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism
Alam, Aftab [Indian Institute of Technology Bombay; Khan, Suffian N [Ames Laboratory; Smirnov, A V [Ames Laboratory; Nicholson, D M [Oak Ridge National Laboratory; Johnson, Duane D [Ames Laboratory
2014-11-01T23:59:59.000Z
The Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an efficient site-centered, electronic-structure technique for addressing an assembly of N scatterers. Wave functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number Lmax=(l,m)max, while scattering matrices, which determine spectral properties, are truncated at Ltr=(l,m)tr where phase shifts ?l>ltr are negligible. Historically, Lmax is set equal to Ltr, which is correct for large enough Lmax but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for Lmax>Ltr with ?l>ltr set to zero [X.-G. Zhang and W. H. Butler, Phys. Rev. B 46, 7433 (1992)]. We present a numerically efficient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R3 process with rank N(ltr+1)2] and includes higher-L contributions via linear algebra [R2 process with rank N(lmax+1)2]. The augmented-KKR approach yields properly normalized wave functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe, and L10 CoPt and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus Lmax for a given Ltr.
Polylithiated (OLi2) functionalized graphane as a potential hydrogen storage material
Hussain, Tanveer; De Sarkar, Abir; Ahuja, Rajeev
2012-01-01T23:59:59.000Z
Hydrogen storage capacity, stability, bonding mechanism and the electronic structure of polylithiated molecules (OLi2) functionalized graphane (CH) has been studied by means of first principle density functional theory (DFT). Molecular dynamics (MD) have confirmed the stability, while Bader charge analysis describe the bonding mechanism of OLi2 with CH. The binding energy of OLi2 on CH sheet has been found to be large enough to ensure its uniform distribution without any clustering. It has been found that each OLi2 unit can adsorb up to six H2 molecules resulting into a storage capacity of 12.90 wt% with adsorption energies within the range of practical H2 storage application.
The spacetime of double field theory: Review, remarks, and outlook
Hohm, Olaf
We review double field theory (DFT) with emphasis on the doubled spacetime and its generalized coordinate transformations, which unify diffeomorphisms and b-field gauge transformations. We illustrate how the composition ...
Herbert, Allan Jerome
1969-01-01T23:59:59.000Z
THE EMPIRICAL RELEVANCE OP THE DEFINITION OP WEALTH AS APPLIED TO THE THEORY OF THE CONSUMPTION FUNCTION A Thesis by ALI AN JEROME HEBERT Submitted to the Graduate College of Texas ASM University in Partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE Ma l96 9 year Maj or Sub)set Economics THE EMPIRICAL RELEVANCE OF THE DEFINITION OF HEALTH AS APPLIED TO THE THEORY OF THE CONSUMPTION FUNCTION A Thesis by ALLAN JEROME HEBERT Approved as to style and content by: a...
Song, Xueyu
density functional theory. The equilibrium interfacial density profiles and interfacial free energies were of density profile. We found that the average interfacial free energy is about 0.78, which is in reasonable of the crystal-melt interface is the interfacial free energy. Experimentally, this quantity can be extracted from
Boyer, Edmond
Dynamical mean-field theory using Wannier functions: A flexible route to electronic structure materials with different degrees of structural and electronic complexity, SrVO3 and BaVS3, are investigated calculations of strongly correlated materials F. Lechermann,1,2, * A. Georges,1 A. Poteryaev,1 S. Biermann,1 M
Vukmirovic, Nenad
2010-01-01T23:59:59.000Z
Petersilka, Density Functional Theory (Springer, New York,Quantum Dots: Theory Nenad Vukmirovi´ and Lin-Wang Wang cdensity functional theory; electronic structure; empirical
Efficient iterative method for solving the Dirac-Kohn-Sham density functional theory
Lin, Lin; Shao, Sihong; E, Weinan
2012-11-06T23:59:59.000Z
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.
Complex-energy approach to sum rules within nuclear density functional theory
Hinohara, Nobuo; Nazarewicz, Witold; Olsen, Erik
2015-01-01T23:59:59.000Z
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...
P. J. Forrester; N. S. Witte
2001-03-21T23:59:59.000Z
Tracy and Widom have evaluated the cumulative distribution of the largest eigenvalue for the finite and scaled infinite GUE in terms of a PIV and PII transcendent respectively. We generalise these results to the evaluation of $\\tilde{E}_N(\\lambda;a) := \\Big $, where $ \\chi_{(-\\infty, \\lambda]}^{(l)} = 1$ for $\\lambda_l \\in (-\\infty, \\lambda]$ and $ \\chi_{(-\\infty, \\lambda]}^{(l)} = 0$ otherwise, and the average is with respect to the joint eigenvalue distribution of the GUE, as well as to the evaluation of $F_N(\\lambda;a) := \\Big $. Of particular interest are $\\tilde{E}_N(\\lambda;2)$ and $F_N(\\lambda;2)$, and their scaled limits, which give the distribution of the largest eigenvalue and the density respectively. Our results are obtained by applying the Okamoto $\\tau$-function theory of PIV and PII, for which we give a self contained presentation based on the recent work of Noumi and Yamada. We point out that the same approach can be used to study the quantities $\\tilde{E}_N(\\lambda;a)$ and $F_N(\\lambda;a)$ for the other classical matrix ensembles.
Empirical Distributions of DFT-Domain Speech Coefficients Based on Estimated Speech Variances
obtained from a short-time discrete Fourier transform (DFT) in the context of speech enhancement frameworks. The distribution of clean speech spectral coefficients is of great importance for speech enhancement algorithmsEmpirical Distributions of DFT-Domain Speech Coefficients Based on Estimated Speech Variances Timo
Using the DFT For Data Analysis MATH 418, PDE LAB Spring 2013
Bardsley, John
use of the discrete Fourier transform (DFT), a way of numerically computing the Fourier transform 1: In the m-file DataAnal.m on the website, the DFT is used to find the frequency components compute the power spectrum, which is defined by P(y) = |fft(y)|2 /N, where N is the number of elements
Density functional theory investigation of 3d, 4d, and 5d 13-atom metal clusters
Piotrowski, Mauricio J.; Piquini, Paulo; Da Silva, Juarez L. F. [Departamento de Fisica, Universidade Federal de Santa Maria, Santa Maria 97105-900, RS (Brazil); Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Cx. Postal 369, Sao Carlos 13560-970, SP (Brazil)
2010-04-15T23:59:59.000Z
The knowledge of the atomic structure of clusters composed by few atoms is a basic prerequisite to obtain insights into the mechanisms that determine their chemical and physical properties as a function of diameter, shape, surface termination, as well as to understand the mechanism of bulk formation. Due to the wide use of metal systems in our modern life, the accurate determination of the properties of 3d, 4d, and 5d metal clusters poses a huge problem for nanoscience. In this work, we report a density functional theory study of the atomic structure, binding energies, effective coordination numbers, average bond lengths, and magnetic properties of the 3d, 4d, and 5d metal (30 elements) clusters containing 13 atoms, M{sub 13}. First, a set of lowest-energy local minimum structures (as supported by vibrational analysis) were obtained by combining high-temperature first-principles molecular-dynamics simulation, structure crossover, and the selection of five well-known M{sub 13} structures. Several new lower energy configurations were identified, e.g., Pd{sub 13}, W{sub 13}, Pt{sub 13}, etc., and previous known structures were confirmed by our calculations. Furthermore, the following trends were identified: (i) compact icosahedral-like forms at the beginning of each metal series, more opened structures such as hexagonal bilayerlike and double simple-cubic layers at the middle of each metal series, and structures with an increasing effective coordination number occur for large d states occupation. (ii) For Au{sub 13}, we found that spin-orbit coupling favors the three-dimensional (3D) structures, i.e., a 3D structure is about 0.10 eV lower in energy than the lowest energy known two-dimensional configuration. (iii) The magnetic exchange interactions play an important role for particular systems such as Fe, Cr, and Mn. (iv) The analysis of the binding energy and average bond lengths show a paraboliclike shape as a function of the occupation of the d states and hence, most of the properties can be explained by the chemistry picture of occupation of the bonding and antibonding states.
Ferrero, Alejandro
2015-01-01T23:59:59.000Z
We analyze the $\\beta$-functions of Yukawa and electromagnetic theories with Lorentz violation (LV) and propose an alternative method to find the scale dependence of the different fields that parametrize such violations. The method of solution consists of decomposing a family of parameters into their irreducible representations and thus generating a group of subfamilies that obey the same symmetries and transformation rules. This method allows us to decouple the differential equations describing the $\\beta$-functions and find out if whether they are positive or not. For a set of parameters describing a Lorentz-violating theory, we expect their associated $\\beta$-functions to be nonnegative or, otherwise, their scale dependence to be weak enough. These conditions rely on the fact that asymptotically-free parameters can leave high imprints of LV at low energies, which are ruled out by observations. Besides imposing some constrains on the coefficients that describe LV, this method can be used to extract irreleva...
Magnetism in undoped ZnS studied from density functional theory
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
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.
Schoendorff, George E.; Windus, Theresa L.; De Jong, Wibe A.
2009-12-12T23:59:59.000Z
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.
Welden, Alicia Rae; Zgid, Dominika
2015-01-01T23:59:59.000Z
One-body Green's function theories implemented on the real frequency axis offer a natural formalism for the unbiased theoretical determination of quasiparticle spectra in molecules and solids. Self-consistent Green's function methods employing the imaginary axis formalism on the other hand can benefit from the iterative implicit resummation of higher order diagrams that are not included when only the first iteration is performed. Unfortunately, the imaginary axis Green's function does not give direct access to the desired quasiparticle spectra, which undermines its utility. To this end we investigate how reliably one can calculate quasiparticle spectra from the Extended Koopmans' Theorem (EKT) applied to the imaginary time Green's function in a second order approximation (GF2). We find that EKT in conjunction with GF2 yields IPs and EAs that systematically underestimate experimental and accurate coupled-cluster reference values for a variety of molecules and atoms. This establishes that the EKT allows one to ...
Landscape of the exact energy functional
Cohen, Aron J
2015-01-01T23:59:59.000Z
One of the great challenges of electronic structure theory is the search for the exact functional of density functional theory (DFT). Its existence is undoubted but it is hard to even conceptualize it as it is a surface in a massively multidimensional space. However, the asymmetric two-site Hubbard model has a two-dimensional universe of density matrices and the exact functional simply becomes a function of two variables whose landscape can be calculated, visualized and explored. This one unique surface contains all the possible physics of any system in this universe. A walk on this landscape, moved to the angle of any one-electron Hamiltonian, gives a valley whose minimum is the exact total energy. We show concrete examples of pure-state density matrices that are not v-representable due to the underlying non-convex nature of the exact functional. Using the Perdew, Parr, Levy and Balduz extension to fractional ensembles we calculate the exact functional for all numbers of electrons. The derivative discontinui...
A. Pelster; H. Kleinert
2000-06-20T23:59:59.000Z
Extending recent work on QED and the symmetric phase of the euclidean multicomponent scalar \\phi^4-theory, we construct the vacuum diagrams of the free energy and the effective energy in the ordered phase of \\phi^4-theory. By regarding them as functionals of the free correlation function and the interaction vertices, we graphically solve nonlinear functional differential equations, obtaining loop by loop all connected and one-particle irreducible vacuum diagrams with their proper weights.
A DFT + U study of cerium solubility in LaZrO. | EMSL
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
solution exhibits a reduced charge state. Citation: Wang XJ, HY Xiao, X Zu, and WJ Weber.2012."A DFT + U study of cerium solubility in La?Zr?O?."Journal of Nuclear Materials...
Achim Kempf; David M. Jackson; Alejandro H. Morales
2014-09-23T23:59:59.000Z
We derive new all-purpose methods that involve the Dirac Delta distribution. Some of the new methods use derivatives in the argument of the Dirac Delta. We highlight potential avenues for applications to quantum field theory and we also exhibit a connection to the problem of blurring/deblurring in signal processing. We find that blurring, which can be thought of as a result of multi-path evolution, is, in Euclidean quantum field theory without spontaneous symmetry breaking, the strong coupling dual of the usual small coupling expansion in terms of the sum over Feynman graphs.
Density Functional Theory for Protein Transfer Free Energy Eric A. Mills and Steven S. Plotkin*
Plotkin, Steven S.
-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
Fayer, Michael D.
(CO2) as a function of density from low density (well below the critical density) to high density ethane, carbon dioxide, and fluoroform as a function of density at two temperatures are presented of input information on the SCF properties obtained from the fluids' equations of state and other tabulated
Burke, Kieron
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
Interaction energies of monosubstituted benzene dimers via nonlocal density functional theory
T. Thonhauser; Aaron Puzder; David C. Langreth
2005-09-15T23:59:59.000Z
We present density-functional calculations for the interaction energy of monosubstituted benzene dimers. Our approach utilizes a recently developed fully nonlocal correlation energy functional, which has been applied to the pure benzene dimer and several other systems with promising results. The interaction energy as a function of monomer distance was calculated for four different substituents in a sandwich and two T-shaped configurations. In addition, we considered two methods for dealing with exchange, namely using the revPBE generalized gradient functional as well as full Hartree-Fock. Our results are compared with other methods, such as Moller-Plesset and coupled-cluster calculations, thereby establishing the usefulness of our approach. Since our density-functional based method is considerably faster than other standard methods, it provides a computational inexpensive alternative, which is of particular interest for larger systems where standard calculations are too expensive or infeasible.
G. Chechin; D. Ryabov; S. Shcherbinin
2015-02-27T23:59:59.000Z
Some exact interactions between vibrational modes in systems with discrete symmetry can be described by the theory of the bushes of nonlinear normal modes (NNMs) [G.M. Chechin, V.P. Sakhnenko. Physica D 117, 43 (1998)]. Each bush represents a dynamical object conserving the energy of the initial excitation. Existence of bushes of NNMs is ensured by some group-theoretical selection rules. In [G.M. Chechin, et al. Int. J. Non-Linear Mech. 38, 1451 (2003)], existence and stability of the bushes of vibrational modes in the simple octahedral model of mass points interacting via Lennard-Jones potential were investigated. In the present paper, we study these dynamical objects by the density functional theory in SF6 molecule which possesses the same symmetry and structure. We have fully confirmed the results previously obtained in the framework of the group theoretical approach and have found some new properties of the bushes of NNMs.
Gross, E.K.U.
of 3d Transition Metals A. Scherz,* E. K. U. Gross, H. Appel, C. Sorg, K. Baberschke, and H. Wende, and a new approximation suggested. But the true value of DFT is in constructing one XC approxi- mation
Phillips, Jordan J., E-mail: philljj@umich.edu; Zgid, Dominika [Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 (United States)
2014-06-28T23:59:59.000Z
We report an implementation of self-consistent Green's function many-body theory within a second-order approximation (GF2) for application with molecular systems. This is done by iterative solution of the Dyson equation expressed in matrix form in an atomic orbital basis, where the Green's function and self-energy are built on the imaginary frequency and imaginary time domain, respectively, and fast Fourier transform is used to efficiently transform these quantities as needed. We apply this method to several archetypical examples of strong correlation, such as a H{sub 32} finite lattice that displays a highly multireference electronic ground state even at equilibrium lattice spacing. In all cases, GF2 gives a physically meaningful description of the metal to insulator transition in these systems, without resorting to spin-symmetry breaking. Our results show that self-consistent Green's function many-body theory offers a viable route to describing strong correlations while remaining within a computationally tractable single-particle formalism.
Quantum field theory in the presence of a medium: Green's function expansions
Kheirandish, Fardin [Department of Physics, Islamic Azad University, Shahreza-Branch, Shahreza (Iran, Islamic Republic of); Salimi, Shahriar [Department of Physics, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)
2011-12-15T23:59:59.000Z
Starting from a Lagrangian and using functional-integration techniques, series expansions of Green's function of a real scalar field and electromagnetic field, in the presence of a medium, are obtained. The parameter of expansion in these series is the susceptibility function of the medium. Relativistic and nonrelativistic Langevin-type equations are derived. Series expansions for Lifshitz energy in finite temperature and for an arbitrary matter distribution are derived. Covariant formulations for both scalar and electromagnetic fields are introduced. Two illustrative examples are given.
Aliaga Salazar, James Wilson
2009-06-02T23:59:59.000Z
. In this study, we are mainly interested in developing a computational framework for the analysis of plate structures comprised of composite or functionally graded materials (FGM) with embedded or surface mounted piezoelectric sensors/actuators. These systems...
Aliaga Salazar, James Wilson
2009-06-02T23:59:59.000Z
Smart materials are very important because of their potential applications in the biomedical, petroleum and aerospace industries. They can be used to build systems and structures that self-monitor to function and adapt to new operating conditions...
Impaired Theory Of Mind for Moral Judgment in High-Functioning Autism
Moran, Joseph M.
High-functioning autism (ASD) is characterized by real-life difficulties in social interaction; however, these individuals often succeed on laboratory tests that require an understanding of another person's beliefs and ...
Jorge L. deLyra
2015-03-24T23:59:59.000Z
A correspondence between arbitrary Fourier series and certain analytic functions on the unit disk of the complex plane is established. The expression of the Fourier coefficients is derived from the structure of complex analysis. The orthogonality and completeness relations of the Fourier basis are derived in the same way. It is shown that the limiting function of any Fourier series is also the limit to the unit circle of an analytic function in the open unit disk. An alternative way to recover the original real functions from the Fourier coefficients, which works even when the Fourier series are divergent, is thus presented. The convergence issues are discussed up to a certain point. Other possible uses of the correspondence established are pointed out.
Ahmadi, Amir Ali
2008-01-01T23:59:59.000Z
Lyapunov's direct method, which is based on the existence of a scalar function of the state that decreases monotonically along trajectories, still serves as the primary tool for establishing stability of nonlinear systems. ...
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
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
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.
Zhang, Yu; Biggs, Jason D.; Healion, Daniel; Govind, Niranjan; Mukamel, Shaul
2012-11-21T23:59:59.000Z
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.
Jorge L. deLyra
2015-05-04T23:59:59.000Z
The results presented in this paper are refinements of some results presented in a previous paper. Three such refined results are presented. The first one relaxes one of the basic hypotheses assumed in the previous paper, and thus extends the results obtained there to a wider class of real functions. The other two relate to a closer examination of the issue of the representability of real functions by their Fourier coefficients. As was shown in the previous paper, in many cases one can recover the real function from its Fourier coefficients even if the corresponding Fourier series diverges almost everywhere. In such cases we say that the real function is still representable by its Fourier coefficients. Here we establish a very weak condition on the Fourier coefficients that ensures the representability of the function by those coefficients. In addition to this, we show that any real function that is absolutely integrable can be recovered almost everywhere from, and hence is representable by, its Fourier coefficients, regardless of whether or not its Fourier series converges. Interestingly, this also provides proof for a conjecture proposed in the previous paper.
J. M. Yao; N. Itagaki; J. Meng
2014-09-19T23:59:59.000Z
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.
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
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.
Volodymyr P. Sergiievskyi; Guillaume Jeanmairet; Maximilien Levesque; Daniel Borgis
2014-06-11T23:59:59.000Z
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.
Beste, Ariana [ORNL; Attalla, Moetaz [CSIRO ICT Center, Australia; Jackson, Phil [CSIRO ICT Center, Australia
2012-01-01T23:59:59.000Z
A meta GGA-DFT study of CO{sub 2} activation in aqueous ammonia solutions, with an emphasis on the reaction barrier and molecularity, has been undertaken using the M06-2X functional with an augmented triple-zeta split-valence basis set (6-311++G(d,p)). Up to five base molecules were treated explicitly in order to establish the effects of solvent catalysis in the chemical capture process. Aqueous free energies of solvation were determined for optimized reactant and transition structures using SM8/M06-2X/6-311++G(d,p). The concept of the solvent pre-complex as presented by Dixon and coworkers (Nguyen, M. T.; Matus, M. H.; Jackson, V. E.; Ngan, V. T.; Rustad, J. R.; Dixon, D. A. J. Phys. Chem. A 2008, 112, 10386-10398) was exploited to account for the energetics of disruption of the hydrogen-bonding solvent nano-network prior to the CO{sub 2} activation step. Selected gas- and aqueous-phase thermodynamic quantities have also been derived.
Covariance analysis of finite temperature density functional theory: symmetric nuclear matter
A. Rios; X. Roca-Maza
2014-08-21T23:59:59.000Z
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.
Communication: Self-interaction correction with unitary invariance in density functional theory
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
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.
Spectral Functions, Maximum Entropy Method and Unconventional Methods in Lattice Field Theory
Chris Allton; Danielle Blythe; Jonathan Clowser
2002-04-26T23:59:59.000Z
We present two unconventional methods of extracting information from hadronic 2-point functions produced by Monte Carlo simulations. The first is an extension of earlier work by Leinweber which combines a QCD Sum Rule approach with lattice data. The second uses the Maximum Entropy Method to invert the 2-point data to obtain estimates of the spectral function. The first approach is applied to QCD data, and the second method is applied to the Nambu--Jona-Lasinio model in (2+1)D. Both methods promise to augment the current approach where physical quantities are extracted by fitting to pure exponentials.
Bochevarov, Arteum D.
We report the performance of eight density functionals (B3LYP, BPW91, OLYP, O3LYP, M06, M06-2X, PBE, and SVWN5) in two Gaussian basis sets (Wachters and Partridge-1 on iron atoms; cc-pVDZ on the rest of atoms) for prediction ...
Pfeifer, Holger
Adsorption of supramolecular building blocks on graphite: A force field and density functional-mail: axel.gross@uni-ulm.de The adsorption of the oligopyridine isomers 2,4'-BTP and 3,3'- BTP on graphite with an C6R-6-type dispersion correction, and the calculated adsorption energies are compared to the results
The Fourier transform solution for the Green's function of monoenergetic neutron transport theory
Barry D. ganapol
2014-03-17T23:59:59.000Z
Nearly 45 years ago, Ken Case published his seminal paper on the singular eigenfunction solution for the Green's function of the monoenergetic neutron transport equation with isotropic scattering. Previously, the solution had been obtained by Fourier transform. While it is apparent the two had to be equivalent, a convincing equivalence proof for general anisotropic scattering remained a challenge until now.
A Hybrid Density Functional Theory for Solvation and Solvent-Mediated Interactions
Jin, Zhehui
2012-01-01T23:59:59.000Z
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 .
Desheng Li
2010-05-26T23:59:59.000Z
In this paper we first construct smooth Morse-Lyapunov functions of attractors for nonsmooth dynamical systems. Then we prove that all open attractor neighborhoods of an attractor have the same homotopy type. Based on this basic fact we finally introduce the concept of critical group for Morse sets of an attractor and establish Morse inequalities and equations.
Li, Xiaozhou; Bond, Andrew D.; Johansson, Kristoffer E.; Van de Streek, Jacco, E-mail: jacco.vandestreek@sund.ku.dk [Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100 (Denmark)
2014-08-01T23:59:59.000Z
The crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide contains an imine tautomer, rather than the previously reported amine tautomer. The tautomers can be distinguished using dispersion-corrected density functional theory calculations and by comparison of calculated and measured {sup 13}C solid-state NMR spectra. The crystal structure of the title compound, C{sub 11}H{sub 13}N{sub 3}O{sub 2}S{sub 2}, has been determined previously on the basis of refinement against laboratory powder X-ray diffraction (PXRD) data, supported by comparison of measured and calculated {sup 13}C solid-state NMR spectra [Hangan et al. (2010 ?). Acta Cryst. B66, 615–621]. The mol@@ecule is tautomeric, and was reported as an amine tautomer [systematic name: N-(5-ethyl-1,3,4-thia@@diazol-2-yl)-p-toluene@@sulfonamide], rather than the correct imine tautomer. The protonation site on the mol@@ecule’s 1,3,4-thia@@diazole ring is indicated by the inter@@molecular contacts in the crystal structure: N—H?O hydrogen bonds are established at the correct site, while the alternative protonation site does not establish any notable inter molecular inter@@actions. The two tautomers provide essentially identical Rietveld fits to laboratory PXRD data, and therefore they cannot be directly distinguished in this way. However, the correct tautomer can be distinguished from the incorrect one by previously reported qu@@anti@@tative criteria based on the extent of structural distortion on optimization of the crystal structure using dispersion-corrected density functional theory (DFT-D) calculations. Calculation of the {sup 13}C SS-NMR spectrum based on the correct imine tautomer also provides considerably better agreement with the measured {sup 13}C SS-NMR spectrum.
K. V. Stepanyantz
2006-08-06T23:59:59.000Z
Contribution of matter fields to the Gell-Mann-Low function for N=1 supersymmetric Yang-Mills theory, regularized by higher covariant derivatives, is obtained using Schwinger-Dyson equations and Slavnov-Tailor identities. A possible deviation of the result from the corresponding contribution in the exact Novikov, Shifman, Vainshtein and Zakharov $\\beta$-function is discussed.
Wilkins, John
Comparison of screened hybrid density functional theory to diffusion Monte Carlo in calculations of total energies of silicon phases and defects Enrique R. Batista,1, * Jochen Heyd,2 Richard G. Hennig,3 for the prediction of defect properties using the Heyd-Scuseria-Ernzerhof HSE screened-exchange hybrid functional
Aquino, Fredy W.; Govind, Niranjan; Autschbach, Jochen
2011-10-01T23:59:59.000Z
Density functional theory (DFT) calculations of NMR chemical shifts and molecular g-tensors with Gaussian-type orbitals are implemented via second-order energy derivatives within the scalar relativistic zeroth order regular approximation (ZORA) framework. Nonhybrid functionals, standard (global) hybrids, and range-separated (Coulomb-attenuated, long-range corrected) hybrid functionals are tested. Origin invariance of the results is ensured by use of gauge-including atomic orbital (GIAO) basis functions. The new implementation in the NWChem quantum chemistry package is verified by calculations of nuclear shielding constants for the heavy atoms in HX (X=F, Cl, Br, I, At) and H2X (X = O, S, Se, Te, Po), and Te chemical shifts in a number of tellurium compounds. The basis set and functional dependence of g-shifts is investigated for 14 radicals with light and heavy atoms. The problem of accurately predicting F NMR shielding in UF6-nCln, n = 1 to 6, is revisited. The results are sensitive to approximations in the density functionals, indicating a delicate balance of DFT self-interaction vs. correlation. For the uranium halides, the results with the range-separated functionals are mixed.
A Theory of the Beam Transfer Function (BTF) with Chromaticity Induced Head-Tail Phase Shift
Fartoukh, S
2007-01-01T23:59:59.000Z
The feasibility of chromaticity determination by measuring head-tail phase shifts has been demonstrated both in the CERN-SPS, at HERA (DESY) and at RHIC (BNL). This method, however, requires to apply sizable transverse kick to the beam which might turn to be detrimental to the LHC performance in view of the tight emittance growth budget allowed for this machine. The aim of this paper is to extend the theory to the case of a coherent beam excitation of small amplitude, in particular at a frequency equal to the beam betatron tune (Phase Locked Loop mode), with, as a result, the possibility of envisaging a chromaticity feed-back system based on this technique for the LHC.
Mark R. Pederson
2014-12-13T23:59:59.000Z
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.
Andreas Härtel; Mathijs Janssen; Sela Samin; René van Roij
2015-03-06T23:59:59.000Z
Capacitive mixing (CAPMIX) and capacitive deionization (CDI) are promising candidates for harvesting clean, renewable energy and for the energy efficient production of potable water, respectively. Both CAPMIX and CDI involve water-immersed porous carbon (supercapacitors) electrodes at voltages of the order of hundreds of millivolts, such that counter-ionic packing is important for the electric double layer (EDL) which forms near the surface of these porous materials. Thus, we propose a density functional theory (DFT) to model the EDL, where the White-Bear mark II fundamental measure theory functional is combined with a mean-field Coulombic and a mean spherical approximation-type correction to describe the interplay between dense packing and electrostatics, in good agreement with molecular dynamics simulations. We discuss the concentration-dependent potential rise due to changes in the chemical potential in capacitors in the context of an over-ideal theoretical description and its impact on energy harvesting and water desalination. Compared to less elaborate mean-field models our DFT calculations reveal a higher work output for blue-energy cycles and a higher energy demand for desalination cycles.
The Theory of Functional Forms of the Consumer Demand System and its Application
Usui, Ikuyasu
2010-01-25T23:59:59.000Z
function U(q) = nY k=1 q#11;kk = q#11;11 q#11;22 q#11;33 #1;#1;#1;q#11;nn , (3) with #11;k > 0 andPnk=1#11;k = 1. Setting up the Lagrangian for this optimiza- 11 tion problem L = U(q) +#21; x#0; nX k=1 pkqk ! (4) = nY k=1 q#11;kk +#21; x#0; nX k=1 pkqk... ......................................... 13 2.1.3 Hicksian Demands ......................................16 2.1.4 Elasticity Relations .....................................18 2.1.5 Curvature .............................................. 28 2.2 Demand System Speci...
Towards time-dependent current-density-functional theory in the non-linear regime
Escartín, J. M.; Vincendon, M.; Romaniello, P.; Dinh, P. M.; Reinhard, P.-G.; Suraud, E.
2015-02-27T23:59:59.000Z
? ? Im [???(r, t)???(r, t)] ? q mc AS(r, t) ?(r, t) , (2b) and are independent of the gauge chosen to represent the electromagnetic potentials. A. The Vignale-Kohn functional in real time Up to second order in spatial derivatives, under the basic... that, while treat- ing the memory instantaneously in time, maintains the dissipating effects of the VK approximation. We have demonstrated the capabilities of the method by apply- ing it to Mg, Ca and Na2 whereby we are modeling a short laser pulse...
A density functional theory model of mechanically activated silyl ester hydrolysis
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 für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098 Kiel (Germany); Center for Nanoscience (CeNS), Geschwister-Scholl-Platz 1, 80539 Munich (Germany); Beyer, Martin K. [Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098 Kiel (Germany) [Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098 Kiel (Germany); Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstraße 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
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.
Wopperer, P; Reinhard, P -G; Suraud, E
2014-01-01T23:59:59.000Z
Various ways to analyze the dynamical response of clusters and molecules to electromagnetic perturbations exist. Particularly rich information can be obtained from measuring the properties of electrons emitted in the course of the excitation dynamics. Such an analysis of electron signals covers total ionization, Photo-Electron Spectra, Photoelectron Angular Distributions, and ideally combined PES/PAD, with a long history in molecular physics, also increasingly used in cluster physics. Recent progress in the design of new light sources (high intensity and/or frequency, ultra short pulses) opens new possibilities for measurements and thus has renewed the interest on the analysis of dynamical scenarios through these observables, well beyond a simple access to a density of states. This, in turn, has motivated many theoretical investigations of the dynamics of electronic emission for molecules and clusters. A theoretical tool of choice is here Time-Dependent Density Functional Theory (TDDFT) propagated in real tim...
Huang, S. [Center for Theoretical Physics, Laboratory for Nuclear Science Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Center for Theoretical Physics, Laboratory for Nuclear Science Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); [Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States); Lissia, M. [Center for Theoretical Physics, Laboratory for Nuclear Science Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Center for Theoretical Physics, Laboratory for Nuclear Science Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); [Istituto Nazionale di Fisica Nucleare, via Ada Negri 18, I-09127 Cagliari (Italy); [Dipartimento di Fisica dell` Universita di Cagliari I-09124 Cagliari (Italy)
1995-07-15T23:59:59.000Z
Within the framework of the operator product expansion and the renormalization group equation, we show that the temperature and chemical potential dependence of the zeroth moment of a spectral function (SF) is completely determined by the one-loop structure in an asymptotically free theory, and in particular in QCD. Logarithmic corrections are found to play an essential role in the derivation. This exact result constrains the shape of SF`s, and implies striking effects near phase transitions. Phenomenological parametrizations of the SF, often used in applications such as the analysis of lattice QCD data or QCD sum rule calculations at finite temperature and baryon density, must satisfy these constraints. We also explicitly illustrate in detail the exact sum rule in the Gross-Neveu model.
TjT^f'Dft Ris#-R-442 Department of Reactor
Tf tf 4 otgiooRfc ©TjT^f'Dft Ris#-R-442 iK Department of Reactor Technology Annual Progress Report-R-442 DEPARTMENT OF REACTOR TECHNOLOGY ANNUAL PROGRESS REPORT 1 January - 31 December 1980 Abstract. The activities of the Department of Reactor Tech- nology at Riso during 1980 are described. The work is presented
Final Technical Report for DE-SC0001878 [Theory and Simulation of Defects in Oxide Materials
Chelikowsky, James R. [University of Texas at Austin] [University of Texas at Austin
2014-04-14T23:59:59.000Z
We explored a wide variety of oxide materials and related problems, including materials at the nanoscale and generic problems associated with oxide materials such as the development of more efficient computational tools to examine these materials. We developed and implemented methods to understand the optical and structural properties of oxides. For ground state properties, our work is predominantly based on pseudopotentials and density functional theory (DFT), including new functionals and going beyond the local density approximation (LDA): LDA+U. To study excited state properties (quasiparticle and optical excitations), we use time dependent density functional theory, the GW approach, and GW plus Bethe-Salpeter equation (GW-BSE) methods based on a many-body Green function approaches. Our work focused on the structural, electronic, optical and magnetic properties of defects (such as oxygen vacancies) in hafnium oxide, titanium oxide (both bulk and clusters) and related materials. We calculated the quasiparticle defect states and charge transition levels of oxygen vacancies in monoclinic hafnia. we presented a milestone G0W0 study of two of the crystalline phases of dye-sensitized TiO{sub 2} clusters. We employed hybrid density functional theory to examine the electronic structure of sexithiophene/ZnO interfaces. To identify the possible effect of epitaxial strain on stabilization of the ferromagnetic state of LaCoO{sub 3} (LCO), we compare the total energy of the magnetic and nonmagnetic states of the strained theoretical bulk structure.
Morzan, Uriel N.; Ramírez, Francisco F.; Scherlis, Damián A., E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires (C1428EHA) (Argentina); Oviedo, M. Belén; Sánchez, Cristián G. [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina)] [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Lebrero, Mariano C. González, E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)] [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)
2014-04-28T23:59:59.000Z
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 matrix—required 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.
Gherman, Benjamin F.
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
Diebold, Ulrike
-terminated TiO2 rutile (011)-1 Â 1 surface shows an undulated surface topography with exposed two-fold O (O2cThe 2 Â 1 reconstruction of the rutile TiO2(011) surface: A combined density functional theory, X for publication 28 October 2008 Available online 5 November 2008 Keywords: Titanium dioxide Surface reconstruction
Bell, Alexis T.
with H2O2 releases HOOÂ· 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 HOOÂ· generation. It is also found that species containing two pca ligands and an H2O2 molecule do
A. B. Pimenov; K. V. Stepanyantz
2007-07-26T23:59:59.000Z
Two-loop Gell-Mann-Low function is calculated for N=1 supersymmetric Yang-Mills theory, regularized by higher covariant derivatives. The integrals, which define it, are shown to be reduced to total derivatives and can be easily calculated analytically.
Johannes Lischner; T. A. Arias
2008-06-27T23:59:59.000Z
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.
Revisiting HgCl2: A Solution- and Solid-State 199Hg NMR and ZORA-DFT Computational Study
Taylor, Robert E; Carver, Colin T; Larsen, Ross E; Dmitrenko, Olga; Bai, Shi; Dybowski, Cecil
2009-01-01T23:59:59.000Z
7 (1997), 333-336. [26] R. E. Taylor, Concepts Magn. Reson.DFT Computational Study R. E. Taylor 1 *, Colin T. Carver2522 USA *Corresponding author: R. E. Taylor Email address:
DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell
Katsumoto, Shingo
DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell- namics (MD) analysis of TiO2/solution in- terfaces related to photocatalysis and dye- sensitized solar
Energy density functional for nuclei and neutron stars
J. Erler; C. J. Horowitz; W. Nazarewicz; M. Rafalski; P. -G. Reinhard
2012-11-27T23:59:59.000Z
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.
Density functional theory study of first-layer adsorption of ZrO2 and HfO2 on Ge(100)
Kummel, Andrew C.
Density functional theory study of first-layer adsorption of ZrO2 and HfO2 on Ge(100) T.J. Grassman on the Ge(100)-4 Â 2 surface. Surface binding geometries of metal-down (OMGe) and oxygen-down (M OGe) were considered, including both adsorbate and displacement geometries of MOGe. Calculated enthalpies
Strain induced lithium functionalized graphane as a high capacity hydrogen storage material
Hussain, Tanveer; Ahuja, Rajeev
2012-01-01T23:59:59.000Z
Strain effects on the stability, electronic structure, and hydrogen storage capacity of lithium-doped graphane (CHLi) have been investigated by stateof-the art first principle density functional theory (DFT). Molecular dynamics MD) simulations have confirmed the stability of Li on graphane sheet when it is subject to 10% of tensile strain. Under biaxial asymmetric strain, the binding energy of Li of graphane (CH) sheet increases by 52% with respect to its bulk's cohesive energy. With 25% doping concentration of Li on CH sheet,the gravimetric density of hydrogen storage is found to reach up to 12.12wt%. The adsorption energies of H2 are found to be within the range of practical H2 storage applications.
DFT study on cysteine adsorption mechanism on Au(111) and Au(110)
Buimaga-Iarinca, Luiza; Floare, Calin G.; Calborean, Adrian; Turcu, Ioan [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)
2013-11-13T23:59:59.000Z
Periodic density functional theory calculations were used to investigate relevant aspects of adsorption mechanisms of cysteine dimers in protonated form on Au(111) and Au(110) surfaces. The projected densities of states are explicitly discussed for all main chemical groups of cysteine, i.e. the amino group (NH2), the thiol group (SH) and the carboxylic group (COOH) to identify differences in adsorption mechanism. Special emphasis is put on the analysis of changes in the electronic structure of molecules adsorbed on Au(111) and Au(110) surfaces as well as the accompanying charge transfer mechanisms at molecule-substrate interaction.
Kaufman-Osborn, Tobin [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States); Chagarov, Evgueni A. [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States); Kummel, Andrew C., E-mail: akummel@ucsd.edu [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States); Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States)
2014-05-28T23:59:59.000Z
Passivation, functionalization, and atomic layer deposition nucleation via H{sub 2}O{sub 2}(g) and trimethylaluminum (TMA) dosing was studied on the clean Ge(100) surface at the atomic level using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Chemical analysis of the surface was performed using x-ray photoelectron spectroscopy, while the bonding of the precursors to the substrate was modeled with density functional theory (DFT). At room temperature, a saturation dose of H{sub 2}O{sub 2}(g) produces a monolayer of a mixture of –OH or –O species bonded to the surface. STS confirms that H{sub 2}O{sub 2}(g) dosing eliminates half-filled dangling bonds on the clean Ge(100) surface. Saturation of the H{sub 2}O{sub 2}(g) dosed Ge(100) surface with TMA followed by a 200?°C anneal produces an ordered monolayer of thermally stable Ge–O–Al bonds. DFT models and STM simulations provide a consistent model of the bonding configuration of the H{sub 2}O{sub 2}(g) and TMA dosed surfaces. STS verifies the TMA/H{sub 2}O{sub 2}/Ge surface has an unpinned Fermi level with no states in the bandgap demonstrating the ability of a Ge–O–Al monolayer to serve as an ideal template for further high-k deposition.
Song, Xueyu
perturbation theory. The free energies of the liquid and solid phases are computed using the fundamental to compute free energies of liquid and solid mixtures and, hence, to study alloy phase behaviors an effective hard-sphere HS system. The free energy is, thus, separated into two parts: one of them is the free
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
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.
Chu, Shih-I; Telnov, Dmitry A.
2009-04-03T23:59:59.000Z
We present a time-dependent density-functional-theory approach for the ab initio study of the effect of correlated multielectron responses on the multiphoton ionization (MPI) of diatomic molecules N2, O2, and F2 in intense ...
Malheiro, Carine; Mendiboure, Bruno; Plantier, Frédéric; Miqueu, Christelle [Université Pau et Pays Adour, CNRS, TOTAL - UMR 5150 – LFC-R – Laboratoire des Fluides Complexes et leurs Réservoirs, BP 1155 – PAU, F-64013 (France)] [Université Pau et Pays Adour, CNRS, TOTAL - UMR 5150 – LFC-R – Laboratoire des Fluides Complexes et leurs Réservoirs, BP 1155 – PAU, F-64013 (France); Blas, Felipe J. [Departamento de Física Aplicada, and Centro de Física Teórica y Matemática FIMAT, Universidad de Huelva, 21071 Huelva (Spain)] [Departamento de Física Aplicada, and Centro de Física Teórica y Matemática FIMAT, Universidad de Huelva, 21071 Huelva (Spain)
2014-04-07T23:59:59.000Z
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.
Silverstein, Daniel W.; Govind, Niranjan; van Dam, Hubertus JJ; Jensen, Lasse
2013-12-10T23:59:59.000Z
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.
Duality Symmetric String and M-Theory
David S. Berman; Daniel C. Thompson
2014-12-09T23:59:59.000Z
We review recent developments in duality symmetric string theory. We begin with the world sheet doubled formalism which describes strings in an extended space time with extra coordinates conjugate to winding modes. This formalism is T-duality symmetric and can accommodate non-geometric T-fold backgrounds which are beyond the scope of Riemannian geometry. Vanishing of the conformal anomaly of this theory can be interpreted as a set of spacetime equations for the background fields. These equations follow from an action principle that has been dubbed Double Field Theory (DFT). We review the aspects of generalised geometry relevant for DFT. We outline recent extensions of DFT and explain how, by relaxing the so-called strong constraint with a Scherk Schwarz ansatz, one can obtain backgrounds that simultaneously depend on both the regular and T-dual coordinates. This provides a purely geometric higher dimensional origin to gauged supergravities that arise from non-geometric compactification. We then turn to M-theory and describe recent progress in formulating an E_{n(n)} U-duality covariant description of the dynamics. We describe how spacetime may be extended to accommodate coordinates conjugate to brane wrapping modes and the construction of generalised metrics in this extend space that unite the bosonic fields of supergravity into a single object. We review the action principles for these theories and their novel gauge symmetries. We also describe how a Scherk Schwarz reduction can be applied in the M-theory context and the resulting relationship to the embedding tensor formulation of maximal gauged supergravities.
Cochrane, Kyle Robert (Ktech Corporation, Albuquerque, NM); Chantrenne, Sophie (SAIC, Albuquerque, NM); Mattsson, Thomas Kjell Rene; Faleev, Sergey V. (SNAMI Inc., AL)
2009-09-01T23:59:59.000Z
The ability to quickly understand and deal with issues on ZR, or to virtually design a future ZX accelerator, requires a physics-based capability to simulate all key pulsed power components. Highly important for gas switches and transmission lines are surface phenomena: thermionic emission, photoemission, field emission, and ion-surface dynamics. These are complex processes even at normal conditions, when coupled to the dynamic environment in pulsed power components, the current state of the art of understanding is not at the level of science based predictive modeling. Modeling efforts at the macroscopic level (finite element based hydrodynamic simulations) require detailed information of these processes to yield more reliable results. This is the final report of an LDRD project in the science of extreme environments investment area; the project was focused on describing the physics of surfaces of materials of interest in pulsed-power components. We have calculated the temperature dependence of work functions for metals from first principles using density functional theory (DFT) as well as investigated the effect of initial oxidation and alloying. By using the GW method, we have gone beyond DFT to calculate work functions for Al. The GW work required base-lining the GW results for different systems, since GW lacks a description of total energy. Lastly, we investigated the more macroscopic physics of how a surface and bulk material responds to a very high current under a short time, representative for current loads in pulsed-power components, with emphasis on materials modeling. These simulations were made using two hydrodynamic codes, ALEGRA and MACH2, in order to focus on the materials models themselves.
Fahleson, Tobias; Norman, Patrick, E-mail: panor@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Università 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 Magnétiques Intenses, UPR3228, CNRS/INSA/UJF/UPS, Toulouse and Grenoble (France)
2013-11-21T23:59:59.000Z
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.
Materials Theory, Modeling and Simulation | ORNL
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Salciccioli, Michael; Yu, Weiting; Barteau, Mark A; Chen, Jingguang; Vlachos, Dion G.
2011-05-25T23:59:59.000Z
Understanding and controlling bond-breaking sequences of oxygenates on transition metal catalysts can greatly impact the utilization of biomass feedstocks for fuels and chemicals. The decomposition of ethylene glycol, as the simplest representative of biomass-derived polyols, was studied via density functional theory (DFT) calculations to identify the differences in reaction pathways between Pt and the more active Ni/Pt bimetallic catalyst. Comparison of the computed transition states indicated three potentially feasible paths from ethylene glycol to C1 oxygenated adsorbates on Pt. While not important on Pt, the pathway to 1,2-dioxyethylene (OCH?CH?O) is favored energetically on the Ni/Pt catalyst. Temperature-programmed desorption (TPD) experiments were conducted with deuterated ethylene glycols for comparison with DFT results. These experiments confirmed that decomposition of ethylene glycol on Pt proceeds via initial O–H bond cleavage, followed by C–H and the second O–H bond cleavages, whereas on the Ni/Pt surface, both O–H bonds are cleaved initially. The results are consistent with vibrational spectra and indicate that tuning of the catalyst surface can selectively control bond breaking. Finally, the significant mechanistic differences in decomposition of polyols compared to that of monoalcohols and hydrocarbons serve to identify general trends in bond scission sequences.
Chemisorption of (CHx and C2Hy) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies
Goddard III, William A.
Chemisorption of (CHx and C2Hy) Hydrocarbons on Pt(111) Clusters and Surfaces from DFT Studies Timo that these hydrocarbons all bind covalently (-bonds) to the surface, in agreement with the studies by Kua and Goddard on small Pt clusters. In nearly every case the structure of the adsorbed hydrocarbon achieves a saturated
The DFT+Umol method and its application to the adsorption of CO on platinum model clusters
Soini, Thomas M.; Krüger, Sven [Department Chemie and Catalysis Research Center, Technische Universität München, 85747 Garching (Germany)] [Department Chemie and Catalysis Research Center, Technische Universität München, 85747 Garching (Germany); Rösch, Notker, E-mail: roesch@mytum.de [Department Chemie and Catalysis Research Center, Technische Universität München, 85747 Garching (Germany) [Department Chemie and Catalysis Research Center, Technische Universität München, 85747 Garching (Germany); Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, No. 16-16 Connexis, Singapore 138632 (Singapore)
2014-05-07T23:59:59.000Z
Semi-local DFT approximations are well-known for their difficulty with describing the correct site preference for the adsorption of CO molecules on (111) surfaces of several late transition metals. To address this problem originating from a residual self-interaction in the CO LUMO, we present the DFT+Umol approach which generalizes the empirical DFT+U correction to fragment molecular orbitals. This correction is applied to examine CO adsorption energies at various sites on the (111) facets of cuboctahedral clusters Pt{sub m}(CO){sub 8} (m = 79, 140, 225). The DFT+Umol correction leaves the electronic ground state of metal clusters, in particular their d-band structure, essentially unchanged, affecting almost exclusively the energy of the CO LUMO. As a result, that correction is significantly stronger for complexes at hollow sites, hence increases the propensity for adsorption at top sites. We also analyze competing edge effects on the (111) facets of the cluster models.
Cox, Stephen J.; Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom) [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Towler, Michael D. [Department of Earth Sciences, University College London Gower Street, London WC1E 6BT (United Kingdom) [Department of Earth Sciences, University College London Gower Street, London WC1E 6BT (United Kingdom); Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Alfè, Dario [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom) [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Earth Sciences, University College London Gower Street, London WC1E 6BT (United Kingdom)
2014-05-07T23:59:59.000Z
High quality reference data from diffusion Monte Carlo calculations are presented for bulk sI methane hydrate, a complex crystal exhibiting both hydrogen-bond and dispersion dominated interactions. The performance of some commonly used exchange-correlation functionals and all-atom point charge force fields is evaluated. Our results show that none of the exchange-correlation functionals tested are sufficient to describe both the energetics and the structure of methane hydrate accurately, while the point charge force fields perform badly in their description of the cohesive energy but fair well for the dissociation energetics. By comparing to ice I{sub h}, we show that a good prediction of the volume and cohesive energies for the hydrate relies primarily on an accurate description of the hydrogen bonded water framework, but that to correctly predict stability of the hydrate with respect to dissociation to ice I{sub h} and methane gas, accuracy in the water-methane interaction is also required. Our results highlight the difficulty that density functional theory faces in describing both the hydrogen bonded water framework and the dispersion bound methane.
J. M. Yao; L. S. Song; K. Hagino; P. Ring; J. Meng
2015-01-29T23:59:59.000Z
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.
Duan, Yuhua; Zhang, Bo; Sorescu, Dan C.; Johnson, Karl; Majzoub, Eric H; Luebke, David R.
2012-07-01T23:59:59.000Z
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 optical–transverse 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 0–900 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.
Kawaguchi, Yoshizo [Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Sasaki, Fumio; Mochizuki, Hiroyuki [Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Ishitsuka, Tomoaki; Tomie, Toshihisa [Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Ootsuka, Teruhisa [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Watanabe, Shuji [Graduate School of Science and Engineering, Yamagata University, 1-4-12, Kojirakawa, Yamagata 990-8560 (Japan); Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Shimoi, Yukihiro [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Yamao, Takeshi; Hotta, Shu [Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)
2013-02-28T23:59:59.000Z
We have investigated electronic states in the valence electron bands for the thin films of three thiophene/phenylene co-oligomer (TPCO) compounds, 2,5-bis(4-biphenylyl)thiophene (BP1T), 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5), and 1,4-bis{l_brace}5-[4-(trifluoromethyl)phenyl]thiophen-2-yl{r_brace}benzene (AC5-CF{sub 3}), by using extreme-UV excited photoelectron spectroscopy (EUPS). By comparing both EUPS spectra and secondary electron spectra between AC5 and AC5-CF{sub 3}, we confirm that CF{sub 3} substitution to AC5 deepens valence states by 2 eV, and increases the ionization energy by 3 eV. From the cut-off positions of secondary electron spectra, the work functions of AC5, AC5-CF{sub 3}, and BP1T are evaluated to be 3.8 eV, 4.8 eV, and 4.0 eV, respectively. We calculate molecular orbital (MO) energy levels by the density functional theory and compare results of calculations with those of experiments. Densities of states obtained by broadening MO levels well explain the overall features of experimental EUPS spectra of three TPCOs.
Al-Hamdani, Yasmine S.; Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Alfè, Dario [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lilienfeld, O. Anatole von [Institute of Physical Chemistry, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Argonne National Laboratories, 9700 S. Cass Avenue, Lemont, Illinois 60439 (United States)
2014-11-14T23:59:59.000Z
Density functional theory (DFT) studies of weakly interacting complexes have recently focused on the importance of van der Waals dispersion forces, whereas the role of exchange has received far less attention. Here, by exploiting the subtle binding between water and a boron and nitrogen doped benzene derivative (1,2-azaborine) we show how exact exchange can alter the binding conformation within a complex. Benchmark values have been calculated for three orientations of the water monomer on 1,2-azaborine from explicitly correlated quantum chemical methods, and we have also used diffusion quantum Monte Carlo. For a host of popular DFT exchange-correlation functionals we show that the lack of exact exchange leads to the wrong lowest energy orientation of water on 1,2-azaborine. As such, we suggest that a high proportion of exact exchange and the associated improvement in the electronic structure could be needed for the accurate prediction of physisorption sites on doped surfaces and in complex organic molecules. Meanwhile to predict correct absolute interaction energies an accurate description of exchange needs to be augmented by dispersion inclusive functionals, and certain non-local van der Waals functionals (optB88- and optB86b-vdW) perform very well for absolute interaction energies. Through a comparison with water on benzene and borazine (B{sub 3}N{sub 3}H{sub 6}) we show that these results could have implications for the interaction of water with doped graphene surfaces, and suggest a possible way of tuning the interaction energy.
X-ray diffraction, spectroscopic and DFT studies of 1-(4-bromophenyl)-3,5-diphenylformazan
Tezcan, H., E-mail: habibe@gazi.edu.tr [Gazi University, Department of Chemistry, Faculty of Education (Turkey); Tokay, N. [Hacettepe University, Department of Chemistry, Faculty of Science (Turkey); Alpaslan, G. [Giresun University, Department of Medical Services and Techniques, Vocational School of Health Services (Turkey); Erdönmez, A. [Ondokuz May?s University, Department of Physics, Faculty of Science and Art (Turkey)
2013-12-15T23:59:59.000Z
The crystal structure of 1-(4-bromophenyl)-3,5-diphenylformazan was determined by X-ray single crystal diffraction technique. The crystals are orthorhombic, a = 23.0788(9), b = 7.9606(3), c = 18.6340(12) Å, Z = 8, sp. gr. Pbca, R{sub 1} = 0.074. The structure was also examined using the density-functional theory. Its structure stability, and frontier molecular orbital components were discussed and the results were compared with X-ray and spectral results. The maximum absorbtion peaks of the UV-vis spectrum of the compound have been calculated using the time-dependent density-functional theory. It was found a good agreement between the calculated and experimental maximum absorption wavelength.
DFT modeling of adsorption onto uranium metal using large-scale parallel computing
Davis, N.; Rizwan, U. [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL (United States)
2013-07-01T23:59:59.000Z
There is a dearth of atomistic simulations involving the surface chemistry of 7-uranium which is of interest as the key fuel component of a breeder-burner stage in future fuel cycles. Recent availability of high-performance computing hardware and software has rendered extended quantum chemical surface simulations involving actinides feasible. With that motivation, data for bulk and surface 7-phase uranium metal are calculated in the plane-wave pseudopotential density functional theory method. Chemisorption of atomic hydrogen and oxygen on several un-relaxed low-index faces of 7-uranium is considered. The optimal adsorption sites (calculated cohesive energies) on the (100), (110), and (111) faces are found to be the one-coordinated top site (8.8 eV), four-coordinated center site (9.9 eV), and one-coordinated top 1 site (7.9 eV) respectively, for oxygen; and the four-coordinated center site (2.7 eV), four-coordinated center site (3.1 eV), and three-coordinated top2 site (3.2 eV) for hydrogen. (authors)
E. Conte; A. Khrennikov; A. Federici; J. P. Zbilut
2007-11-06T23:59:59.000Z
We developed a new method for analysis of fundamental brain waves as recorded by EEG. To this purpose we introduce a Fractal Variance Function that is based on the calculation of the variogram. The method is completed by using Random Matrix Theory. Some examples are given.
Rocca, Jorge J.
Partial Oxidation of Propylene Catalyzed by VO3 Clusters: A Density Functional Theory Study Zhe are carried out to investigate partial oxidation of propylene over neutral VO3 clusters. CdC bond cleavage of propylene with VO3 at room temperature. Formation of hydrogen transfer products H2O + VO2C3H4, CH2d
Paris-Sud XI, Université de
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
Javaid, Saqib [EMMG, Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); National Centre of Physics, Islamabad (Pakistan); Javed Akhtar, M., E-mail: javedakhtar6@gmail.com [EMMG, Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)
2014-07-14T23:59:59.000Z
We have investigated the behavior of orthoferrite LaFeO{sub 3} at ambient conditions and under pressure using DFT (generalized gradient approximation (GGA))?+?U approach. Ground state electronic (band gap) and magnetic properties are considerably improved due to the Hubbard correction. Moreover, the experimentally observed pressure-driven phase transition, namely, the simultaneous occurrence of spin crossover, isostructural volume collapse, and drastic reduction in electrical resistance (electronic phase transition) is nicely described by GGA?+?U calculations. In particular, despite a sharp drop in resistance, a small band gap still remains in the low spin state indicating an insulator to semiconductor phase transition, in good agreement with the experiments but in contrast to GGA, which predicts metallic behavior in low spin state. We discuss the origin of variation in electronic structure of LaFeO{sub 3} in low spin state as obtained from GGA to GGA?+?U methods. These results emphasize the importance of correlation effects in describing the pressure-driven phase transition in LaFeO{sub 3} and other rare-earth orthoferrites.
Xue, H. T.; Tang, F. L., E-mail: tfl03@mails.tsinghua.edu.cn [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Science and Technology on Surface Engineering Laboratory, Lanzhou Institute of Physics, Lanzhou 730000 (China); Lu, W. J.; Li, X. K.; Zhang, Y. [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Feng, Y. D. [Science and Technology on Surface Engineering Laboratory, Lanzhou Institute of Physics, Lanzhou 730000 (China)
2014-08-07T23:59:59.000Z
The phase diagram of the CuInSe{sub 2}-CuGaSe{sub 2} pseudobinary system was determined using a combination of special quasirandom structure approach, ab initio density functional theory calculations, and thermodynamic modelling. It is shown that the CuIn{sub 1?x}Ga{sub x}Se{sub 2} solution phase has a tendency to phase separation at low temperature. The calculated consolute temperature is 485?K. It is found that both the binodal and spinodal curves are significantly asymmetric and on both curves there are a local maximum and a local minimum, which have not been reported in the previous studies. Our phase diagram can well explain the finding that the inhomogeneity of CuIn{sub 0.25}Ga{sub 0.75}Se{sub 2} is higher than that of CuIn{sub 0.75}Ga{sub 0.25}Se{sub 2} at the same temperature, while the previous phase diagrams cannot. Hence, our phase diagram should be more reliable and applicable.
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
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.
siloxanes form only 2 covalent bonds, in a `bridge' mode with adjacent Ti4+ ions on the TiO2 surface of binding enthalpies at the DFT B3LYP/(LACVP/6-31G**) level of theory indicating that the `bridge' binding optical, electrical, magnetic and mechanical properties of semiconductor materials. For example, dye
Baer, Marcel D.; Kuo, I-F W.; Tobias, Douglas J.; Mundy, Christopher J.
2014-07-17T23:59:59.000Z
The propensities of the water self ions, H3O+ and OH- , for the air-water interface has implications for interfacial acid-base chemistry. Despite numerous experimental and computational studies, no consensus has been reached on the question of whether or not H3O+ and/or OH- prefer to be at the water surface or in the bulk. Here we report a molecular dynamics simulation study of the bulk vs. interfacial behavior of H3O+ and OH- that employs forces derived from density functional theory with a generalized gradient approximation exchangecorrelation functional (specifically, BLYP) and empirical dispersion corrections. We computed the potential of mean force (PMF) for H3O+ as a function of the position of the ion in a 215-molecule water slab. The PMF is flat, suggesting that H3O+ has equal propensity for the air-water interface and the bulk. We compare the PMF for H3O+ to our previously computed PMF for OH- adsorption, which contains a shallow minimum at the interface, and we explore how differences in solvation of each ion at the interface vs. the bulk are connected with interfacial propensity. We find that the solvation shell of H3O+ is only slightly dependent on its position in the water slab, while OH- partially desolvates as it approaches the interface, and we examine how this difference in solvation behavior is manifested in the electronic structure and chemistry of the two ions. DJT was supported by National Science Foundation grant CHE-0909227. CJM was supported by the U.S. Department of Energy‘s (DOE) Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the Department of Energy by Battelle. The potential of mean force required resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DEAC05-00OR22725. The remaining simulations and analysis used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. at at Lawrence Berkeley National Laboratory. MDB is grateful for the support of the Linus Pauling Distinguished Postdoctoral Fellowship Program at PNNL.
Interfacial Properties and Design of Functional Energy Materials
Sumpter, Bobby G [ORNL] [ORNL; Liang, Liangbo [ORNL] [ORNL; Nicolai, Adrien [Rensselaer Polytechnic Institute (RPI)] [Rensselaer Polytechnic Institute (RPI); Meunier, V. [Rensselaer Polytechnic Institute (RPI)] [Rensselaer Polytechnic Institute (RPI)
2014-01-01T23:59:59.000Z
The vital importance of energy to society continues to demand a relentless pursuit of energy responsive materials that can bridge fundamental chemical structures at the molecular level and achieve improved functionality, such as efficient energy conversion/storage/transmission, over multiple length scales. This demand can potentially be realized by harnessing the power of self-assembly a spontaneous process where molecules or much larger entities form ordered aggregates as a consequence of predominately non-covalent (weak) interactions. Self-assembly is the key to bottom-up design of molecular devices, because the nearly atomic-level control is very difficult to realize in a top-down, e.g., lithographic approach. However, while function (e.g., charge mobility) in simple systems such as single crystals can often be predicted, predicting the function of the great variety of self-assembled molecular architectures is complicated by the lack of understanding and control over nanoscale interactions, mesoscale architectures, and macroscale (long-range) order. To establish a foundation toward delivering practical solutions, it is critical to develop an understanding of the chemical and physical mechanisms responsible for the self-assembly of molecular and hybrid materials on various substrates. Typically molecular self-assembly involves poorly understood non-covalent intermolecular and substrate-molecule interactions compounded by local and/or collective influences from the substrate atomic lattice (symmetry and/or topological features) and electronic structure. Thus, progress towards unraveling the underlying physicochemical processes that control the structure and macroscopic physical, mechanical, electrical, and transport properties of materials increasingly requires tight integration of theory, modeling and simulation with precision synthesis, advanced experimental characterization, and device measurements. In this mode, theory and simulation can greatly accelerate the process of materials discovery by providing atomic level understanding of physicochemical phenomena and for making predictions of trends. In particular, this approach can provide understanding, prediction and exploration of new materials and conditions before they are realized in the lab, to illuminate connections between experimental observations, and help identify new materials for targeted synthesis. Toward this end, Density Functional Theory (DFT) can provide a suitable computational framework for investigating the inter- and intramolecular bonding, molecular conformation, charge and spin configurations that are intrinsic to self-assembly of molecules on substrates. This Account highlights recent advances in using an integrated approach based on DFT and scanning probe microscopy [STM(s), AFM] to study/develop electronic materials formed from the self-assembly of molecules into supramolecular or polymeric architectures on substrates. Here it is the interplay between molecular interactions and surface electrons that is used to control the final architecture and subsequent bulk properties of the two-dimensional patterns/assemblies. Indeed a rich variety of functional energy materials become possible.
Ghadar, Yasaman; Clark, Aurora E.
2012-02-02T23:59:59.000Z
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 water–pentane dimer has been determined using coupled-cluster theory with single double (triple) excitations [CCSD(T)], 2nd order Möller 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 water–pentane 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).
Kilina, Svetlana [Los Alamos National Laboratory; Tretiak, Sergei [Los Alamos National Laboratory; Sykora, Milan [Los Alamos National Laboratory; Albert, Victor [UNIV OF FLORIDA; Badaeva, Ekaterina [UNIV OF WASHINGTON; Koposov, Alexey [UNIV OF WASHINGTON
2008-01-01T23:59:59.000Z
New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the Ru(II) complex to the surface of a semiconductor, a linking bridge -- a carboxyl group -- needs to be added to one or two of the 2,2'-bipyridine (bpy) ligands. Such changes in the ligand structure affect electronic and optical properties and, consequently, the charge transfer reactivity of Ru(II)-systems. In this study, we analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the [Ru(bpy){sub 3}]{sup 2+} complex. First principle calculations based on density functional theory (DFT) and time dependent DFT (TDDFT) are used to simulate the ground and excited-state properties, respectively, of functionalized Ru-complexes in the gas phase and acetonitrile solution. In addition, an effective Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states in all molecules. All theoretical results nicely complement and allow for detailed interpretation of experimental absorption spectra of Ru-complexes that have been done in parallel with our theoretical investigations. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show that deprotonation of the carboxyl group in the Ru-complexes results in a slight blue shift and decrease of oscillator strengths of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotonated complexes demonstrate strong agreement if the theoretical calculations are performed with the addition of a dielectric continuum model. A polar solvent is found to play an important role in calculations of optical spectra: it stabilizes the energy of states localized on the carboxyl or carboxylate groups. Thus, the excited-state structure of the functionalized Ru-complexes, specifically in the case of the deprotonated functions, can be accurately modeled by TDDFT with the addition of a dielectric continuum in simulations.
Pisani, Pablo
2015-01-01T23:59:59.000Z
We present a pedagogical exposition of some applications of functional methods in quantum field theory: we use heat-kernel and zeta-function techniques to study the Casimir effect, the pair production in strong electric fields, quantum fields at finite temperature and beta-functions for a self-interacting scalar field, QED and pure Yang-Mills theories. The more recent application to the UV/IR mixing phenomenon in noncommutative theories is also discussed in this framework.
Molecular simulations studies of gas adsorption in metal–organic frameworks
Chen, Linjiang
2014-06-30T23:59:59.000Z
Using computational tools ranging from molecular simulations – including both Monte Carlo and molecular dynamics methods – to quantum mechanical (QM) calculations (primarily at density functional theory (DFT) level), ...
Water and Carbon Dioxide Adsorption at Olivine Surfaces. | EMSL
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and Carbon Dioxide Adsorption at Olivine Surfaces. Water and Carbon Dioxide Adsorption at Olivine Surfaces. Abstract: Plane-wave density functional theory (DFT) calculations were...
Defining Active Catalyst Structure and Reaction Pathways from...
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of a detailed operando XAFS and density functional theory (DFT) based ab initio molecular dynamics (AIMD) investigation of the proposed mechanism of dehydrogenation of...
Statistical mechanical theory for steady state systems. VII. Nonlinear theory
Attard, Phil
Statistical mechanical theory for steady state systems. VII. Nonlinear theory Phil Attard School May 2007; published online 2 July 2007 The second entropy theory for nonequilibrium thermodynamics explicitly as a type of the Green-Kubo equilibrium time correlation function. The theory is illustrated
Mutombo, P.; Romanyuk, O., E-mail: romanyuk@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16200 Prague (Czech Republic)
2014-05-28T23:59:59.000Z
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.
Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense Helium
Militzer, Burkhard
Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense integral Monte Carlo (PIMC) and density func- tional molecular dynamics (DFT-MD), are applied to study hot excitation mecha- nisms that determine their behavior at high temperature. The helium atom has two ionization
Chu, Iek-Heng; Cheng, Hai-Ping
2013-01-01T23:59:59.000Z
We have studied the energetics, electronic structure, optical excitation, and electron relaxation of dinitromethane molecules (CH$_{2}$N$_{2}$O$_{4}$) adsorbed on semiconducting carbon nanotubes (CNTs) of chiral index (n,0) (n=7, 10, 13, 16, 19). Using first-principles density functional theory (DFT) with generalized gradient approximations and van der Waals corrections, we have calculated adsorption energies of dinitropentylpyrene, in which the dinitromethane is linked to the pyrene via an aliphatic chain, on a CNT. A 75.26 kJ/mol binding energy has been found, which explains why such aliphatic chain-pyrene units can be and have been used in experiments to bind functional molecules to CNTs. The calculated electronic structures show that the dinitromethane introduces a localized state inside the band gap of CNT systems of n=10, 13, 16 and 19; such a state can trap an electron when the CNT is photoexcited. We have therefore investigated the dynamics of intra-band relaxations using the reduced density matrix fo...
Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D.; Aryanpour, Masoud; Reeder, Richard J.; Parise, John B.; Phillips, Brian L. (SBU); (Penn)
2012-03-15T23:59:59.000Z
Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on {gamma}-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on {gamma}-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on {gamma}-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 {angstrom} and 3.09 {angstrom}, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 {+-} 0.01 {angstrom} with a coordination number of 4 and a second shell of As-Al at 3.13 {+-} 0.04 {angstrom} with a coordination number of 2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of {gamma}-alumina as predicted by density functional theory (DFT) calculation.
Duan, Yuhua; Parlinski, K.
2011-01-01T23:59:59.000Z
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.
Baik, Mu-Hyun
1,2-CF bond activation of perfluoroarenes and alkylidene isomers of titanium. DFT analysis of the CeF bond activation pathway and rotation of the titanium alkylidene moiety José G. Andino, Hongjun Received in revised form 26 July 2011 Accepted 27 July 2011 Keywords: Alkylidene Titanium CeF bond
Frank Discussion of the Status of Ground-state Orbital-free DFT
Karasiev, Valentin V
2015-01-01T23:59:59.000Z
F.E. Harris has been a significant partner in our work on orbital-free density functional approximations for use in ab initio molecular dynamics. Here we mention briefly the essential progress on single-point functionals since our original paper (2006). Then we focus on the advantages and limitations of generalized gradient approximation (GGA) non-interacting kinetic-energy functionals. We reconsider the constraints provided by near-origin conditions in atomic-like systems and their relationship to regularized versus physical external potentials. Then we seek the best empirical GGA for the non-interacting KE for a modest-sized set of molecules with a well-defined near-origin behavior of their densities. The search is motivated by a desire for insight into GGA limitations and for a target for constraint-based development.
Herbert, John
-Functional Description of the 1 La State in Polycyclic Aromatic Hydrocarbons: Charge-Transfer Character in Disguise? Ryan aromatic hydrocarbons (PAHs) includes two singlet excited states that are often denoted 1 La and 1 Lb. Time operator into short- and long-range components.8,15,21À23 While conventional TD-DFT's propensity
Canonical density matrix perturbation theory
Niklasson, Anders M N; Rubensson, Emanuel H; Rudberg, Elias
2015-01-01T23:59:59.000Z
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.
Accurate nuclear masses from a three parameter Kohn-Sham DFT approach (BCPM)
Baldo, M.; Robledo, L. M.; Schuck, P.; Vinas, X. [Instituto Nazionale di Fisica Nucleare, Sezione di Catania, Via Santa Sofia 64, I-95123 Catania (Italy); Dep. Fisica Teorica (Modulo 15), Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Inst. de Physique Nucleaire,CNRS-IN2P3 and Univ. Paris-Sud, 91406 Orsay cedex (France); Departament d'Estructura i Conastituents de la Materia and Institut de Ciencies del Cosmos Facultat de Fisica, Universitat de Barcelona, Marti i Franques 1, 08028 (Spain)
2012-10-20T23:59:59.000Z
Given the promising features of the recently proposed Barcelona-Catania-Paris (BCP) functional [1], it is the purpose of this work to still improve on it. It is, for instance, shown that the number of open parameters can be reduced from 4-5 to 2-3, i.e. by practically a factor of two without deteriorating the results.
Functionalized Graphene Nanoroads for Quantum Well Device. |...
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Nanoroads for Quantum Well Device. Functionalized Graphene Nanoroads for Quantum Well Device. Abstract: Using density functional theory, a series of calculations of structural and...
Spin dependent parton distributions and structure functions
W. Bentz; I. C. Cloet; T. Ito; A. W. Thomas; K. Yazaki
2007-09-10T23:59:59.000Z
Nuclear parton distributions and structure functions are determined in an effective chiral quark theory. We also discuss an extension of our model to fragmentation functions.
Kim, Inkoo; Lee, Yoon Sup, E-mail: yslee@kaist.edu [Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)
2014-10-28T23:59:59.000Z
We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues.
Laird, Brian Bostian
1992-06-01T23:59:59.000Z
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 Ashcroft [Phys. Rev. A 3 9...
Battenfeld, Ingo
2008-01-01T23:59:59.000Z
This thesis presents Topological Domain Theory as a powerful and flexible framework for denotational semantics. Topological Domain Theory models a wide range of type constructions and can interpret many computational features. Furthermore, it has...We begin by describing the categories of Topological Domain Theory, and their categorical structure. In particular, we recover the basic constructions of domain theory, such as products, function spaces, fixed points and recursive types, in the context of Topological Domain Theory....As a central contribution, we give a detailed account of how computational effects can be modelled in Topological Domain Theory. Following recent work of Plotkin and Power, who proposed to construct effect monads via free algebra functors, this is done by showing that free algebras for a large class of parametrised equational theories exist in Topological Domain Theory. These parametrised equational theories are expressive enough to generate most of the standard examples of effect monads. Moreover, the free algebras in Topological Domain Theory are obtained by an explicit inductive construction, using only basic topological and set-theoretical principles....We also give a comparison of Topological and Classical Domain Theory. The category of omega-continuous dcpos embeds into Topological Domain Theory, and we prove that this embedding preserves the basic domain-theoretic constructions in most cases. We show that the classical powerdomain constructions on omega-continuous dcpos, including the probabilistic powerdomain, can be recovered in Topological Domain Theory....Finally, we give a synthetic account of Topological Domain Theory. We show that Topological Domain Theory is a specific model of Synthetic Domain Theory in the realizability topos over Scott's graph model. We give internal characterisations of the categories of Topological Domain Theory in this realizability topos, and prove the corresponding categories to be internally complete and weakly small. This enables us to show that Topological Domain Theory can model the polymorphic lambda-calculus, and to obtain a richer collection of free algebras than those constructed earlier....In summary, this thesis shows that Topological Domain Theory supports a wide range of semantic constructions, including the standard domain-theoretic constructions, computational effects and polymorphism, all within a single setting....
DFT+U Study of CeO2 and Its Native Defects
Huang, Bolong; Gillen, Roland; Robertson, John
2014-10-14T23:59:59.000Z
in solid state fuel cells2, as a catalyst3-6, as a high-dielectric constant gate oxide7, and in resistance random access memories (ReRAM)8. Many properties of CeO2 are determined by its intrinsic defects9-23 and the unusual behavior of the semi-core Ce 4f... averaging scheme46 for spin- orbital coupling effect. The RRKJ method is chosen as optimization of pseudopotentials47. The PBE functional was chosen for PBE+U calculations with a kinetic cutoff energy of 750eV, which expands the valence electrons states...
DFT+U Study of Polaronic Conduction in Li2O2 and Li2CO3: Implications for Li-Air Batteries
Thygesen, Kristian
DFT+U Study of Polaronic Conduction in Li2O2 and Li2CO3: Implications for Li-Air Batteries J. M-air batteries are known to be Li2O2 and residual Li2CO3. Recent experiments indicate that the charge transport through these materials is the main limiting factor for the battery performance. It has been also shown
Makrlik, Emanuel [Czech University of Life Sciences, Prague, Kamy´cká; Toman, Petr [Institute of Macromolecular Chemistry, Prague; Vanura, Petr [Institute of Chemical Technology, Prague, Czech Republic; Moyer, Bruce A [ORNL
2013-01-01T23:59:59.000Z
From extraction experiments and c-activity measurements, the extraction constant corresponding to the equilibrium Cs+ (aq) + I (aq) + 1 (org),1Cs+ (org) + I (org) taking place in the two-phase water-phenyltrifluoromethyl sulfone (abbrev. FS 13) system (1 = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, org = FS 13 phase) was evaluated as logKex (1Cs+, I) = 2.1 0.1. Further, the stability constant of the 1Cs+ complex in FS 13 saturated with water was calculated for a temperature of 25 C: log borg (1Cs+) = 9.9 0.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1Cs+ was derived. In the resulting 1Cs+ complex, the central cation Cs+ is bound by eight bond interactions to six oxygen atoms of the respective 18-crown-6 moiety and to two carbons of the corresponding two benzene rings of the parent ligand 1 via cation p interaction.
Pivovar, B. S.; Edson, J. B.; Macomber, C. S.; Long, H.; Boncella, J. M.
2012-01-01T23:59:59.000Z
The mechanism of the thermal decomposition of a series of alkyl trimethyl ammonium hydroxides ([RMe{sub 3}N][OH], R = Et, n-Pr, i-Bu, PhCH{sub 2}, Me{sub 3}CCH{sub 2}) was studied using TGA, evolved gas analysis and NMR spectroscopy due to the importance of these and related ions in anion exchange fuel cell membranes. Isotopic labeling with deuterium showed that deprotonation of the methyl groups of the ammonium ions by deuteroxide establishes a rapid equilibrium between the tetraalkyl ammonium ions and the nitrogen ylide species and water that scrambles the deuterium with the proton on the methyl groups. The products of the thermal decomposition when R = Et, n-Pr, i-Bu are predominately olefins arising from Hoffmann elimination, while the neopentyl substituted ammonium ion gives only neopentyl trimethyl amine and methanol, the products of S{sub N}2 attack of hydroxide on the methyl groups. DFT studies of these reactions confirm the relative activation barriers that are observed in the experimental decomposition studies.
Friebel, Daniel; Viswanathan, Venkatasubramanian; Miller, Daniel James; Anniyev, Toyli; Ogasawara, Hirohito; Larsen, Ask Hjorth; O'Grady, Christopher P.; Norskov, Jens K.; Nilsson, Anders
2012-05-31T23:59:59.000Z
We have studied the effect of nanostructuring in Pt monolayer model electrocatalysts on a Rh(111) single-crystal substrate on the adsorption strength of chemisorbed species. In situ high energy resolution fluorescence detection X-ray absorption spectroscopy at the Pt L(3) edge reveals characteristic changes of the shape and intensity of the 'white-line' due to chemisorption of atomic hydrogen (H(ad)) at low potentials and oxygen-containing species (O/OH(ad)) at high potentials. On a uniform, two-dimensional Pt monolayer grown by Pt evaporation in ultrahigh vacuum, we observe a significant destabilization of both H(ad) and O/OH(ad) due to strain and ligand effects induced by the underlying Rh(111) substrate. When Pt is deposited via a wet-chemical route, by contrast, three-dimensional Pt islands are formed. In this case, strain and Rh ligand effects are balanced with higher local thickness of the Pt islands as well as higher defect density, shifting H and OH adsorption energies back toward pure Pt. Using density functional theory, we calculate O adsorption energies and corresponding local ORR activities for fcc 3-fold hollow sites with various local geometries that are present in the three-dimensional Pt islands.
Morse Theory One of the most cited
Landweber, Laura
Morse Theory J. Milnor One of the most cited books in mathemat- ics, John Milnor's expo- sition of Morse theory has been the most impor- tant book on the subject for more than forty years. Morse theory for Advanced Study, and Princeton published his Topological Methods in the Theory of Functions of a Complex
Michael A. Idowu
2014-10-15T23:59:59.000Z
We intimate deeper connections between the Riemann zeta and gamma functions than often reported and further derive a new formula for expressing the value of $\\zeta(2n+1)$ in terms of zeta at other fractional points. This paper also establishes and presents new expository notes and perspectives on zeta function theory and functional analysis. In addition, a new fundamental result, in form of a new function called omega $\\Omega(s)$, is introduced to analytic number theory for the first time. This new function together with some of its most fundamental properties and other related identities are here disclosed and presented as a new approach to the analysis of sums of generalised harmonic series, related alternating series and polygamma functions associated with Riemann zeta function.
Boolean Theory laws proof Number Theory Character Theory
Hehner, Eric C.R.
Review Boolean Theory laws proof Number Theory Character Theory Bunches Sets Strings Lists for loop 1/109 #12;Review Boolean Theory laws proof Number Theory Character Theory Bunches Sets Strings with exit for loop 2/109 #12;Review Boolean Theory laws proof Number Theory Character Theory Bunches Sets
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
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.
Bret, A.; Gremillet, L.; Benisti, D. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain and Instituto de Investigaciones Energeticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain); CEA, DAM, DIF, F-91297 Arpajon (France)
2010-03-15T23:59:59.000Z
Following a recent Letter by Bret et al. [Phys. Rev. Lett. 100, 205008 (2008)], we present a detailed report of the entire unstable k spectrum of a relativistic collisionless beam-plasma system within a fully kinetic framework. In contrast to a number of previously published studies, our linear analysis makes use of smooth momentum distribution functions of the Maxwell-Juettner form. The three competing classes of instabilities, namely, two-stream, filamentation, and oblique modes, are dealt with in a unified manner, no approximation being made regarding the beam-plasma densities, temperatures, and drift energies. We investigate the hierarchy between the competing modes, paying particular attention to the relatively poorly known quasielectrostatic oblique modes in the regime where they govern the system. The properties of the fastest growing oblique modes are examined in terms of the system parameters and compared to those of the dominant two-stream and filamentation modes.
Oeiras, R. Y.; Silva, E. Z. da [Institute of Physics “Gleb Wataghin”, University of Campinas-Unicamp, 13083-859 Campinas, SP (Brazil)] [Institute of Physics “Gleb Wataghin”, University of Campinas-Unicamp, 13083-859 Campinas, SP (Brazil)
2014-04-07T23:59:59.000Z
Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed ?-bond (MpB) model describes unsaturated carbons that introduce a mobile ?-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials.
Discontinuous Lyapunov Functions for Nonasymptotic Stability Analysis
Paris-Sud XI, Université de
Discontinuous Lyapunov Functions for Nonasymptotic Stability Analysis A. Polyakov Inria Lille of discontinuous control systems using discontinuous Lyapunov functions. Elements of Filippov theory of generalized derivatives and non-smooth Lyapunov functions are considered. The generalized Lyapunov theorems
Boolean Theory laws proof Number Theory Character Theory
Hehner, Eric C.R.
construction induction Recursive Program Definition construction induction Theory Design and Implementation Definition construction induction Theory Design and Implementation data theory program theory Data Recursive Data Definition construction induction Recursive Program Definition construction induction Theory
Dey, Abhishek; Chow, Marina; /Stanford U., Chem. Dept.; Taniguchi, Kayoko; /Wako, RIKEN; Lugo-Mas, Priscilla; Davin, Steven; /Washington U., Seattle; Maeda, Mizuo; /SLAC,; Kovacs, Julie A.; /Washington U., Seattle; Odaka, Masafumi; /Wako, RIKEN; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC, SSRL
2006-09-28T23:59:59.000Z
The geometric and electronic structure of the active site of the non-heme iron enzyme nitrile hydratase (NHase) is studied using sulfur K-edge XAS and DFT calculations. Using thiolate (RS{sup -})-, sulfenate (RSO{sup -})-, and sulfinate (RSO{sub 2}{sup -})-ligated model complexes to provide benchmark spectral parameters, the results show that the S K-edge XAS is sensitive to the oxidation state of S-containing ligands and that the spectrum of the RSO- species changes upon protonation as the S-O bond is elongated (by {approx}0.1 {angstrom}). These signature features are used to identify the three cysteine residues coordinated to the low-spin Fe{sup III} in the active site of NHase as CysS{sup -}, CysSOH, and CysSO{sub 2}{sup -} both in the NO-bound inactive form and in the photolyzed active form. These results are correlated to geometry-optimized DFT calculations. The pre-edge region of the X-ray absorption spectrum is sensitive to the Z{sub eff} of the Fe and reveals that the Fe in [FeNO]{sup 6} NHase species has a Z{sub eff} very similar to that of its photolyzed Fe{sup III} counterpart. DFT calculations reveal that this results from the strong {pi} back-bonding into the {pi}* antibonding orbital of NO, which shifts significant charge from the formally t{sub 2}{sup 6} low-spin metal to the coordinated NO.
Tretiak, Sergei [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the complex to the surface of a semiconductor, a linking bridge - a carboxyl group - is added to one or two of the 2,2{prime}-bipyridine ligands. Such changes in the ligand structure, indeed, affect electronic and optical properties and consequently, the charge transfer reactivity of Ru-systems. In this study, we apply both theoretical and experimental approaches to analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the Ru(II) bipyridine complex. First principle calculations based on density functional theory (DFT) and linear response time dependent density functional theory (TDDFT) are used to simulate the ground and excited-state structures of functionalized Ru-complexes in the gas phase, as well as in acetonitrile solution. In addition, an inelaborate Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states. All theoretical results nicely complement experimental absorption spectra of Ru-complexes and contribute to their interpretation. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show a high probability of deprotonation of the carbboxyl group in the Ru-complexes resulted in a slight blue shift and decrease of intensities of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotanated complexes demonstrate strong agreement when acetonitrile solvent is used in simulations. A polar solvent is found to play an important role in calculations of optical spectra: it stabilizes the energy of states localized on the carboxyl or carboxylate groups eliminating artificial charge transport states, which typically appear in TDDFT calculations. Thus, it is validated that the excited-state structure of the functionalized Ru-complexes, specifically in the case of the deprotonated functions, can be accurately modeled by TDDFT with the addition of a dielectric continuum in simulations.
Al-Saadi, Abdulaziz A. H.
2009-05-15T23:59:59.000Z
The structure, potential energy functions and vibrational spectra of several cyclic and bicyclic molecules have been investigated using several spectroscopic techniques and high-level ab initio and density functional theory (DFT) calculations. Laser...
Hydrogen activation, diffusion, and clustering on CeO{sub 2}(111): A DFT+U study
Fernández-Torre, Delia [Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Instituto de Estructura de la Materia, CSIC, C/ Serrano 121, E-28006 Madrid (Spain); Carrasco, Javier [CIC Energigune, Albert Einstein 48, 01510 Miñano, Álava (Spain); Instituto de Catálisis y Petroleoquímica, CSIC, C/ Marie Curie 2, E-28049 Madrid (Spain); Ganduglia-Pirovano, M. Verónica [Instituto de Catálisis y Petroleoquímica, CSIC, C/ Marie Curie 2, E-28049 Madrid (Spain); Pérez, Rubén, E-mail: ruben.perez@uam.es [Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid (Spain)
2014-07-07T23:59:59.000Z
We present a comprehensive density functional theory+U study of the mechanisms underlying the dissociation of molecular hydrogen, and diffusion and clustering of the resulting atomic species on the CeO{sub 2}(111) surface. Contrary to a widely held view based solely on a previous theoretical prediction, our results show conclusively that H{sub 2} dissociation is an activated process with a large energy barrier ?1.0 eV that is not significantly affected by coverage or the presence of surface oxygen vacancies. The reaction proceeds through a local energy minimum – where the molecule is located close to one of the surface oxygen atoms and the H–H bond has been substantially weaken by the interaction with the substrate –, and a transition state where one H atom is attached to a surface O atom and the other H atom sits on-top of a Ce{sup 4+} ion. In addition, we have explored how several factors, including H coverage, the location of Ce{sup 3+} ions as well as the U value, may affect the chemisorption energy and the relative stability of isolated OH groups versus pair and trimer structures. The trimer stability at low H coverages and the larger upward relaxation of the surface O atoms within the OH groups are consistent with the assignment of the frequent experimental observation by non-contact atomic force and scanning tunneling microscopies of bright protrusions on three neighboring surface O atoms to a triple OH group. The diffusion path of isolated H atoms on the surface goes through the adsorption on-top of an oxygen in the third atomic layer with a large energy barrier of ?1.8 eV. Overall, the large energy barriers for both, molecular dissociation and atomic diffusion, are consistent with the high activity and selectivity found recently in the partial hydrogenation of acetylene catalyzed by ceria at high H{sub 2}/C{sub 2}H{sub 2} ratios.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
the Fock matrix is constructed and then diagonalized. To build the Fock matrix, Fast Fourier Transforms are used to tranform orbitals from the plane wave basis ( where the...
2015-03-12T23:59:59.000Z
Cellar theory. A. Eremenko. March 12, 2015. The temperature on the Earth surface at a given place experiences roughly speaking periodic fluctuation, daily and ...
Quantum theory Bohrification: topos theory and quantum theory
Spitters, Bas
Quantum theory Bohrification: topos theory and quantum theory Bas Spitters Domains XI, 9/9/2014 Bas Spitters Bohrification: topos theory and quantum theory #12;Quantum theory Point-free Topology The axiom, Krein-Millman, Alaoglu, Hahn-Banach, Gelfand, Zariski, ... Bas Spitters Bohrification: topos theory
Green functions and Macdonald functions associated to complex reflection groups
Shoj, Toshiaki
Green functions and Macdonald functions associated to complex reflection groups Toshiaki Shoji Department of Mathematics Science University of Tokyo Noda, Chiba 2788510, Japan 1. Introduction 1.1. Green functions are introduced by J.A. Green [G] in 1955, in connection with the representation theory of general
Walsh, Timothy Francis; Reese, Garth M.; Bhardwaj, Manoj Kumar
2004-08-01T23:59:59.000Z
This manual describes the theory behind many of the constructs in Salinas. For a more detailed description of how to use Salinas , we refer the reader to Salinas, User's Notes. Many of the constructs in Salinas are pulled directly from published material. Where possible, these materials are referenced herein. However, certain functions in Salinas are specific to our implementation. We try to be far more complete in those areas. The theory manual was developed from several sources including general notes, a programer-notes manual, the user's notes and of course the material in the open literature.
A COMPLEXITY THEORY OF CONSTRUCTIBLE FUNCTIONS AND ...
2014-06-01T23:59:59.000Z
Jun 1, 2014 ... very naturally in the algebraic geometry over real and complex .... construction of a sequence of parametrized polynomial systems with a ...
Density-Functional Theory for Complex Fluids
Wu, Jianzhong
. This generic methodology is built upon a mathematical theorem that states, for an equilibrium system at a given modeling of the microscopic struc- tures and phase behavior of soft-condensed matter. The methodol- ogy to the one-body density profile Grand potential: the free energy of an open system at fixed volume
Theory and applications of Bessel functions
Wasson, William Albert
1949-01-01T23:59:59.000Z
negat1ve integer. Then equations (1-2) are equivalent to d=& ~ C=(. '=C~= . -=o, I 3 C, = ? C, ? art(&u+~V c ? 0" c. &si g~(yt. K)('C+W ~) "Cu+i) C () C'. I Cv+') (IC=], 2, 3, " ~~* K! I (v+ tc+i) Thus a formal solut1on of Bessel's equation 1...s y=y C?X' = P ("?X"' K p'f AA' ( ? I) Q / cv+)w (xI (~q . . . ) K! p(v+z~i) wh1ch takes a simpler form if we further choose the arb1, trary I C to be Then we have the particular formal / (u+i) ~ solution P tLK Z (x/=Z /xX h-3 K! / P+K I...
Density functional theory study of acetaldehyde hydrodeoxygenation...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
hydroxyls, which can recombine into a water molecule weakly bound at the Mo site. A terminal oxygen (Ot) defect site thus forms after water desorption. CH3CHO adsorbs at the...
Functional Keldysh theory of spin torques
Duine, R. A.; Nunez, A. S.; Sinova, Jairo; MacDonald, A. H.
2007-01-01T23:59:59.000Z
stochastic Landau-Lifschitz-Gilbert equation with spin-transfer torques. We calculate the Gilbert damping parameter alpha and the nonadiabatic spin transfer torque parameter beta for a model ferromagnet. We find that beta not equal alpha, in agreement...
Quantum Field Theory and Representation Theory
Woit, Peter
Quantum Field Theory and Representation Theory Peter Woit woit@math.columbia.edu Department of Mathematics Columbia University Quantum Field Theory and Representation Theory p.1 #12;Outline of the talk · Quantum Mechanics and Representation Theory: Some History Quantum Field Theory and Representation Theory
Smooth Field Theories and Homotopy Field Theories
Wilder, Alan Cameron
2011-01-01T23:59:59.000Z
1 . . . . . . . . 4 Categories of Field Theories 4.1 Functorto super symmetric field theories. CRM Proceedings and0-dimensional super symmetric field theories. preprint 2008.
On Conformal Field Theory and Number Theory
Huang, An
2011-01-01T23:59:59.000Z
Frontiers in Number Theory, Physics, and Ge- ometry II. (Witten, Quantum Field Theory, Crassmannians, and AlgebraicJ. Polchinski, String Theory, Vol. 1, Cambridge Univ.
Covariant Hamiltonian Field Theory
Jürgen Struckmeier; Andreas Redelbach
2012-05-22T23:59:59.000Z
A consistent, local coordinate formulation of covariant Hamiltonian field theory is presented. Whereas the covariant canonical field equations are equivalent to the Euler-Lagrange field equations, the covariant canonical transformation theory offers more general means for defining mappings that preserve the form of the field equations than the usual Lagrangian description. It is proved that Poisson brackets, Lagrange brackets, and canonical 2-forms exist that are invariant under canonical transformations of the fields. The technique to derive transformation rules for the fields from generating functions is demonstrated by means of various examples. In particular, it is shown that the infinitesimal canonical transformation furnishes the most general form of Noether's theorem. We furthermore specify the generating function of an infinitesimal space-time step that conforms to the field equations.
Bevir, Mark
2013-01-01T23:59:59.000Z
Marsh, eds. , The State: Theory and Issues. Basingstoke, UK:Passion,” Administra- tive Theory & Praxis 18 (1996), 97–?Public Administration Theory,” Administrative Theory &
Holographic Quenches and Fermionic Spectral Functions
N. Callebaut; B. Craps; F. Galli; D. C. Thompson; J. Vanhoof; J. Zaanen; Hongbao Zhang
2014-11-04T23:59:59.000Z
Using holographic methods we investigate the behaviour of fermionic spectral functions of strongly coupled 2+1 dimensional field theories as both temperature and chemical potential are quenched.
Mathematical quantization of Hamiltonian field theories
A. V. Stoyanovsky
2015-02-04T23:59:59.000Z
We define the renormalized evolution operator of the Schr\\"odinger equation in the infinite dimensional Weyl-Moyal algebra during a time interval for a wide class of Hamiltonians depending on time. This leads to a mathematical definition of quantum field theory $S$-matrix and Green functions. We show that for renormalizable field theories, our theory yields the renormalized perturbation series of perturbative quantum field theory. All the results are based on the Feynman graph series technique.
Classical Theorems in Noncommutative Quantum Field Theory
M. Chaichian; M. Mnatsakanova; A. Tureanu; Yu. Vernov
2006-12-12T23:59:59.000Z
Classical results of the axiomatic quantum field theory - Reeh and Schlieder's theorems, irreducibility of the set of field operators and generalized Haag's theorem are proven in SO(1,1) invariant quantum field theory, of which an important example is noncommutative quantum field theory. In SO(1,3) invariant theory new consequences of generalized Haag's theorem are obtained. It has been proven that the equality of four-point Wightman functions in two theories leads to the equality of elastic scattering amplitudes and thus the total cross-sections in these theories.
Lithium Local Pseudopotential Using
Petta, Jason
Lithium Local Pseudopotential Using DFT Sergio Orozco Student Advisor: Chen Huang Faculty Mentor Lithium LPS Test Lithium LPS #12;Density Functional Theory (DFT) Successful quantum mechanical approach (1979) #12;Building LPS for Lithium Create a LPS using NLPS density for Lithium Test LPS by comparing
The Globular Cluster Luminosity Function
Dean E. McLaughlin
2003-02-14T23:59:59.000Z
The main aspects of the globular cluster luminosity function needing to be explained by a general theory of cluster formation are reviewed, and the importance of simultaneously understanding globular cluster systematics (the fundamental plane) within such a theory is pointed out.
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
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.
A New Glauber Theory based on Multiple Scattering Theory
Masanobu Yahiro; Kosho Minomo; Kazuyuki Ogata; Mitsuji Kawai
2008-09-26T23:59:59.000Z
Glauber theory for nucleus-nucleus scattering at high incident energies is reformulated so as to become applicable also for the scattering at intermediate energies. We test validity of the eikonal and adiabatic approximations used in the formulation, and discuss the relation between the present theory and the conventional Glauber calculations with either the empirical nucleon-nucleon profile function or the modified one including the in-medium effect.
A viscoplastic theory for braze alloys
Neilsen, M.K.; Burchett, S.N.; Stone, C.M.; Stephens, J.J.
1996-04-01T23:59:59.000Z
A new viscoplastic theory for CusilABA and other braze alloys has been developed. Like previous viscoplastic theories,this new theory uses a hyperbolic sine function of effective stress in its kinetic equation for the inelastic strain rate. This new theory has an internal state variable which accounts for isotropic hardening and recovery and a second-order, internal state tensor which accounts for kinematic hardening and recovery. Unlike previous theories, the new theory uses evolution equations for the state variables which describe competing mechanisms of power law hardening and static recovery. The evolution equations used in previous theories describe competing mechanisms of linear hardening, dynamic and static recovery. The new viscoplastic theory was implemented in several finite element codes and used in several metal-to-ceramic brazing simulations. Two approaches for obtaining material parameters for the new viscoplastic theory were developed.
ORAL QUAL SYLLABUS: SET THEORY; ERGODIC THEORY
ORAL QUAL SYLLABUS: SET THEORY; ERGODIC THEORY SAMUEL COSKEY Set Theory. #15; Basic set theory's theorem { there exists an Aronsajn tree { Shanin's root system lemma (#2;2) #15; Descriptive set theory of set theory (Jech 12,13) { Mostowski's collapsing theorem { relativization and absolute formulas { re
David J. Gross; Washington Taylor
2001-06-27T23:59:59.000Z
We describe the ghost sector of cubic string field theory in terms of degrees of freedom on the two halves of a split string. In particular, we represent a class of pure ghost BRST operators as operators on the space of half-string functionals. These BRST operators were postulated by Rastelli, Sen, and Zwiebach to give a description of cubic string field theory in the closed string vacuum arising from condensation of a D25-brane in the original tachyonic theory. We find a class of solutions for the ghost equations of motion using the pure ghost BRST operators. We find a vanishing action for these solutions, and discuss possible interpretations of this result. The form of the solutions we find in the pure ghost theory suggests an analogous class of solutions in the original theory on the D25-brane with BRST operator Q_B coupling the matter and ghost sectors.
Designer Gravity and Field Theory Effective Potentials
Hertog, Thomas; Horowitz, Gary T. [Department of Physics, UCSB, Santa Barbara, California 93106 (United States)
2005-06-10T23:59:59.000Z
Motivated by the anti-de Sitter conformal field theory correspondence, we show that there is remarkable agreement between static supergravity solutions and extrema of a field theory potential. For essentially any function V({alpha}) there are boundary conditions in anti--de Sitter space so that gravitational solitons exist precisely at the extrema of V and have masses given by the value of V at these extrema. Based on this, we propose new positive energy conjectures. On the field theory side, each function V can be interpreted as the effective potential for a certain operator in the dual field theory.
Orondo, Peter Omondi
2012-01-01T23:59:59.000Z
We provide a first principles analysis of the physics and thermodynamics of interstitial hydrogen in metal. By utilizing recent advances in Density Functional Theory (DFT) to get state energies of the metal-hydrogen system, ...
A survey of codes and algorithms used in NERSC material science allocations
Wang, Lin-Wang
2006-01-01T23:59:59.000Z
of different codes. Each symbol represents one code. Fig.2:computer time used for codes belong to different categories.Functional Theory (DFT) codes. Fig.3: The number of codes
Heterometallic MIIRuIII 2 Compounds Constructed from
Gao, Song
-like interpenetrating network that exhibits ferromagnetic ordering below 4.6 K. The density functional theory (DFT that examples of 3d-4d and 3d-5d coordination polymers in the field of molecular magnetism are mostly
A Polarizable QM/MM Explicit Solvent Model for Computational Electrochemistry in Water
Wang, Lee-Ping
We present a quantum mechanical/molecular mechanical (QM/MM) explicit solvent model for the computation of standard reduction potentials E[subscript 0]. The QM/MM model uses density functional theory (DFT) to model the ...
CO[subscript 2] hydrogenation to formic acid on Ni(111)
Peng, Guowen
Periodic, self-consistent, density functional theory (DFT) calculations are employed to study CO[subscript 2] hydrogenation on Ni(111). CO[subscript 2] hydrogenation with H adsorbed on the surface and with H absorbed in ...
Optical Constants and Inelastic Electron-Scattering Data for 17 Elemental Wolfgang S. M. Wernera...
Magee, Joseph W.
reflection electron energy-loss spectroscopy REELS spectra, provides reliable optical data from the near. One data set is obtained from density functional theory DFT calculations and gives from the infrared
Exciton/Charge-transfer Electronic Couplings in Organic Semiconductors
Difley, Seth
Charge transfer (CT) states and excitons are important in energy conversion processes that occur in organic light emitting devices (OLEDS) and organic solar cells. An ab initio density functional theory (DFT) method for ...
Yuhua Duan
2012-01-01T23:59:59.000Z
Alkali metal zirconates could be used as solid sorbents for CO{sub 2} capture. The structural, electronic, and phonon properties of Na{sub 2}ZrO{sub 3}, K{sub 2}ZrO{sub 3}, Na{sub 2}CO{sub 3}, and K{sub 2}CO{sub 3} are investigated by combining the density functional theory with lattice phonon dynamics. The thermodynamics of CO{sub 2} absorption/desorption reactions of these two zirconates are analyzed. The calculated results show that their optimized structures are in a good agreement with experimental measurements. The calculated band gaps are 4.339 eV (indirect), 3.641 eV (direct), 3.935 eV (indirect), and 3.697 eV (direct) for Na{sub 2}ZrO{sub 3}, K{sub 2}ZrO{sub 3}, Na{sub 2}CO{sub 3}, and K{sub 2}CO{sub 3}, respectively.The calculated phonon dispersions and phonon density of states for M{sub 2}ZrO{sub 3} and M{sub 2}CO{sub 3} (M = K, Na, Li) revealed that from K to Na to Li, their frequency peaks are shifted to high frequencies due to the molecular weight decreased from K to Li. From the calculated reaction heats and relationships of free energy change versus temperatures and CO{sub 2} pressures of the M{sub 2}ZrO{sub 3} (M = K, Na, Li) reacting with CO{sub 2}, we found that the performance of Na{sub 2}ZrO{sub 3} capturing CO{sub 2} is similar to that of Li{sub 2}ZrO{sub 3} and is better than that of K{sub 2}ZrO{sub 3}. Therefore, Na{sub 2}ZrO{sub 3} and Li{sub 2}ZrO{sub 3} are good candidates of high temperature CO{sub 2} sorbents and could be used for post combustion CO{sub 2} capture technologies.
Wave function derivation of the JIMWLK equation
Alexey V. Popov
2008-12-16T23:59:59.000Z
Using the stationary lightcone perturbation theory, we propose the complete and careful derivation the JIMWLK equation. We show that the rigorous treatment requires the knowledge of a boosted wave function with second order accuracy. Previous wave function approaches are incomplete and implicitly used the time ordered perturbation theory, which requires a usage of an external target field.
Physics 221B: Solution to HW # 8 Quantum Field Theory
Murayama, Hitoshi
Physics 221B: Solution to HW # 8 Quantum Field Theory 1) Bosonic Grand-Partition Function The solution to this problem is outlined clearly in the beginning of the lecture notes `Quantum Field Theory II
Instanton Effects in Orbifold ABJM Theory
Masazumi Honda; Sanefumi Moriyama
2014-06-28T23:59:59.000Z
We study the partition function of the orbifold ABJM theory on $S^3$, which is the $\\mathcal{N}=4$ necklace quiver Chern-Simons-matter theory with alternating levels, in the Fermi gas formalism. We find that the grand potential of the orbifold ABJM theory is expressed explicitly in terms of that of the ABJM theory. As shown previously, the ABJM grand potential consists of the naive but primary non-oscillatory term and the subsidiary infinitely-replicated oscillatory terms. We find that the subsidiary oscillatory terms of the ABJM theory actually give a non-oscillatory primary term of the orbifold ABJM theory. Also, interestingly, the perturbative part in the ABJM theory results in a novel instanton contribution in the orbifold theory. We also present a physical interpretation for the non-perturbative instanton effects.
A Naturally Renormalized Quantum Field Theory
S. Rouhani; M. V. Takook
2006-07-07T23:59:59.000Z
It was shown that quantum metric fluctuations smear out the singularities of Green's functions on the light cone [1], but it does not remove other ultraviolet divergences of quantum field theory. We have proved that the quantum field theory in Krein space, {\\it i.e.} indefinite metric quantization, removes all divergences of quantum field theory with exception of the light cone singularity [2,3]. In this paper, it is discussed that the combination of quantum field theory in Krein space together with consideration of quantum metric fluctuations, results in quantum field theory without any divergences.
Mathematical niche theory Mathematical niche theory
Meszéna, Géza
Mathematical niche theory Mathematical niche theory G´eza Mesz´ena1 Gy¨orgy Barab´as2 KalleUniversity of Turku MMEE 2011, Groningen #12;Mathematical niche theory Outline 1 Introduction 2 Core theory 3 Ways of niche segragation 4 Controversies #12;Mathematical niche theory Introduction Why are there so
Walsh, Timothy Francis; Reese, Garth M.; Bhardwaj, Manoj Kumar
2011-11-01T23:59:59.000Z
Salinas provides a massively parallel implementation of structural dynamics finite element analysis, required for high fidelity, validated models used in modal, vibration, static and shock analysis of structural systems. This manual describes the theory behind many of the constructs in Salinas. For a more detailed description of how to use Salinas, we refer the reader to Salinas, User's Notes. Many of the constructs in Salinas are pulled directly from published material. Where possible, these materials are referenced herein. However, certain functions in Salinas are specific to our implementation. We try to be far more complete in those areas. The theory manual was developed from several sources including general notes, a programmer notes manual, the user's notes and of course the material in the open literature.
Conjugate flow action functionals
Venturi, Daniele, E-mail: daniele-venturi@brown.edu [Division of Applied Mathematics, Brown University, Rhode Island 02912 (United States)] [Division of Applied Mathematics, Brown University, Rhode Island 02912 (United States)
2013-11-15T23:59:59.000Z
We present a new general framework to construct an action functional for a non-potential field theory. The key idea relies on representing the governing equations relative to a diffeomorphic flow of curvilinear coordinates which is assumed to be functionally dependent on the solution field. Such flow, which will be called the conjugate flow, evolves in space and time similarly to a physical fluid flow of classical mechanics and it can be selected in order to symmetrize the Gâteaux derivative of the field equations with respect to suitable local bilinear forms. This is equivalent to requiring that the governing equations of the field theory can be derived from a principle of stationary action on a Lie group manifold. By using a general operator framework, we obtain the determining equations of such manifold and the corresponding conjugate flow action functional. In particular, we study scalar and vector field theories governed by second-order nonlinear partial differential equations. The identification of transformation groups leaving the conjugate flow action functional invariant could lead to the discovery of new conservation laws in fluid dynamics and other disciplines.
Bevir, Mark
2013-01-01T23:59:59.000Z
Management and Organization Theory: From Panopticon toand covering both organization theory and changing patternsTrust in Organizations: Frontiers of Theory and Research (
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Theory and Software Home People Science Highlights Publications Seminars & Meetings Opportunities Advisory Committee Theory and Software Group (X-ray Science Division) The Theory...
Smooth Field Theories and Homotopy Field Theories
Wilder, Alan Cameron
2011-01-01T23:59:59.000Z
CHAPTER 3. FIELD THEORIES Definition 3.2.1. A smooth fielda ’top down’ definition of field theories. Taking as ourin the following. Definition A field theory is a symmetric
Theory and Modeling of Weakly Bound/Physisorbed Materials for...
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No. W-7405-Eng-48. Outline * Storage by physisorption: - CNT, fullerenes, carbon aerogels - Doping, Decorating, Charging * Accuracy of Methods: DFT, QMC and Quantum Chemistry...
Computer Stochastics in Scalar Quantum Field Theory
C. B. Lang
1993-12-01T23:59:59.000Z
This is a series of lectures on Monte Carlo results on the non-perturbative, lattice formulation approach to quantum field theory. Emphasis is put on 4D scalar quantum field theory. I discuss real space renormalization group, fixed point properties and logarithmic corrections, partition function zeroes, the triviality bound on the Higgs mass, finite size effects, Goldstone bosons and chiral perturbation theory, and the determination of scattering phase shifts for some scalar models.
Modified Fourier expansions: theory, construction and applications
Adcock, Ben
2010-10-12T23:59:59.000Z
Modified Fourier expansions present an alternative to more standard algorithms for the approximation of nonperiodic functions in bounded domains. This thesis addresses the theory of such expansions, their effective construction and computation...
Advanced topics in control systems theory II
Nesic, Dragan
Advanced topics in control systems theory II Lecture notes from FAP 2005 Editors: Antonio Lor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 1.8.2 Inverted Pendulum.4 The desired energy function Hd with kv = 0. . . . . . . . . . . . . . . . . . 32 1.5 Closed-loop responses
A Count of Classical Field Theory Graphs
Gordon Chalmers
2005-07-28T23:59:59.000Z
A generating function is derived that counts the number of diagrams in an arbitrary scalar field theory. The number of graphs containing any number $n_j$ of $j$-point vertices is given. The count is also used to obtain the number of classical graphs in gauge theory and gravity.
M. Aslam Chaudhry
1999-01-01T23:59:59.000Z
Two representations of the extended gamma functions ? 2,0 0,2 [(b,x)] are proved. These representations are exploited to find a transformation relation between two Fox’s H-functions. These results are used to solve Fox’s H-function in terms of Meijer’s G-function for certain values of the parameters. A closed form representation of the kernel of the Bessel type integral transform is also proved. 1.
Equivalence Relations in Set Theory, Computation Theory and Complexity Theory
Equivalence Relations in Set Theory, Computation Theory and Complexity Theory Denable Equivalence-preserving transformations Unitary equivalence of unitary operators Conformal equivalence of Riemann surfaces These are analytic (1 1 with parameters) equivalence relations on Polish spaces (think of the reals) #12;Equivalence
Effective Hamiltonian Constraint from Group Field Theory
Etera R. Livine; Daniele Oriti; James P. Ryan
2011-04-28T23:59:59.000Z
Spinfoam models provide a covariant formulation of the dynamics of loop quantum gravity. They are non-perturbatively defined in the group field theory (GFT) framework: the GFT partition function defines the sum of spinfoam transition amplitudes over all possible (discretized) geometries and topologies. The issue remains, however, of explicitly relating the specific form of the group field theory action and the canonical Hamiltonian constraint. Here, we suggest an avenue for addressing this issue. Our strategy is to expand group field theories around non-trivial classical solutions and to interpret the induced quadratic kinematical term as defining a Hamiltonian constraint on the group field and thus on spin network wave functions. We apply our procedure to Boulatov group field theory for 3d Riemannian gravity. Finally, we discuss the relevance of understanding the spectrum of this Hamiltonian operator for the renormalization of group field theories.
Liouville theory with a central charge less than one
Ribault, Sylvain
2015-01-01T23:59:59.000Z
We determine the spectrum and correlation functions of Liouville theory with a central charge less than (or equal) one. This completes the definition of Liouville theory for all complex values of the central charge. The spectrum is always spacelike, and there is no consistent timelike Liouville theory. We also study the non-analytic conformal field theories that exist at rational values of the central charge. Our claims are supported by numerical checks of crossing symmetry. We provide Python code for computing Virasoro conformal blocks, and correlation functions in Liouville theory and (generalized) minimal models.
Liouville theory with a central charge less than one
Sylvain Ribault; Raoul Santachiara
2015-03-06T23:59:59.000Z
We determine the spectrum and correlation functions of Liouville theory with a central charge less than (or equal) one. This completes the definition of Liouville theory for all complex values of the central charge. The spectrum is always spacelike, and there is no consistent timelike Liouville theory. We also study the non-analytic conformal field theories that exist at rational values of the central charge. Our claims are supported by numerical checks of crossing symmetry. We provide Python code for computing Virasoro conformal blocks, and correlation functions in Liouville theory and (generalized) minimal models.
Ozkanlar, Abdullah; Cape, Jonathan L.; Hurst, James K.; Clark, Aurora E.
2011-09-05T23:59:59.000Z
Density functional theory (DFT) has been used to investigate the plausibility of water addition to the simple mononuclear ruthenium complexes, [(NH{sub 3}){sub 3}(bpy)Ru=O]{sup 2+}/{sup 3+} and [(NH{sub 3}){sub 3}(bpy)RuOH]{sup 3+}, in which the OH fragment adds to the 2,2{prime}-bipyridine (bpy) ligand. Activation of bpy toward water addition has frequently been postulated within the literature, although there exists little definitive experimental evidence for this type of 'covalent hydration'. In this study, we examine the energetic dependence of the reaction upon metal oxidation state, overall spin state of the complex, as well as selectivity for various positions on the bipyridine ring. The thermodynamic favorability is found to be highly dependent upon all three parameters, with free energies of reaction that span favorable and unfavorable regimes. Aqueous addition to [(NH{sub 3}){sub 3}(bpy)Ru=O]{sup 3+} was found to be highly favorable for the S = 1/2 state, while reduction of the formal oxidation state on the metal center makes the reaction highly unfavorable. Examination of both facial and meridional isomers reveals that when bipyridine occupies the position trans to the ruthenyl oxo atom, reactivity toward OH addition decreases and the site preferences are altered. The electronic structure and spectroscopic signatures (EPR parameters and simulated spectra) have been determined to aid in recognition of 'covalent hydration' in experimental systems. EPR parameters are found to uniquely characterize the position of the OH addition to the bpy as well as the overall spin state of the system.
Some convolution products in Quantum Field Theory
Herintsitohaina Ratsimbarison
2006-12-05T23:59:59.000Z
This paper aims to show constructions of scale dependence and interaction on some probabilistic models which may be revelant for renormalization theory in Quantum Field Theory. We begin with a review of the convolution product's use in the Kreimer-Connes formalism of perturbative renormalization. We show that the Wilson effective action can be obtained from a convolution product propriety of regularized Gaussian measures on the space of fields. Then, we propose a natural C*-algebraic framework for scale dependent field theories which may enhance the conceptual approach to renormalization theory. In the same spirit, we introduce a probabilistic construction of interacting theories for simple models and apply it for quantum field theory by defining a partition function in this setting.
Composite Photon Theory Versus Elementary Photon Theory
Walton A. Perkins
2015-03-02T23:59:59.000Z
The purpose of this paper is to show that the composite photon theory measures up well against the Standard Model's elementary photon theory. This is done by comparing the two theories area by area. Although the predictions of quantum electrodynamics are in excellent agreement with experiment (as in the anomalous magnetic moment of the electron), there are some problems, such as the difficulty in describing the electromagnetic field with the four-component vector potential because the photon has only two polarization states. In most areas the two theories give similar results, so it is impossible to rule out the composite photon theory. Pryce's arguments in 1938 against a composite photon theory are shown to be invalid or irrelevant. Recently, it has been realized that in the composite theory the antiphoton does not interact with matter because it is formed of a neutrino and an antineutrino with the wrong helicity. This leads to experimental tests that can determine which theory is correct.
acid derivative functions: Topics by E-print Network
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stem cell (hESC)-derived neurons engineered to be specifically activated by light Fortuna, Miguel A. 22 Functional Determinants in Higher Derivative Lagrangian Theories...
Improved methodology for refolding functional TGF-beta Superfamily ligands
Shumaker, Stephanie D.
2009-01-01T23:59:59.000Z
C. M. ; Mechanisms of Protein Folding 2000, 1, 1-28. 11.structure is critical to protein folding and function. Welandscape theory of protein folding asserts that evolution
Correlation of Structure and Function of Zinc Metalloproteins...
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of Structure and Function of Zinc Metalloproteins Via a Combined NMRMolecular Theory Approach Investigative Team: NMR: Andrew S. Lipton - PI (PNNL) and Paul D. Ellis...
Redundant axioms in the definition of Bregman functions
Jan 22, 2002 ... REDUNDANT AXIOMS IN THE DEFINITION OF BREGMAN ...... some new results on the theory of Bregman functions, Mathematics of ...
Wave function as geometric entity
B. I. Lev
2011-02-10T23:59:59.000Z
A new approach to the geometrization of the electron theory is proposed. The particle wave function is represented by a geometric entity, i.e., Clifford number, with the translation rules possessing the structure of Dirac equation for any manifold. A solution of this equation is obtained in terms of geometric treatment. Interference of electrons whose wave functions are represented by geometric entities is considered. New experiments concerning the geometric nature of electrons are proposed.
Chu, Shih-I; Carrera, Juan J.
2009-06-17T23:59:59.000Z
stabilized narrow-band continuous-wave #1;cw#2; laser used for the actual spectroscopy. However, suitable narrow-band-width cw sources rarely exist at high frequencies #3;10#4;, such as vacuum-ultraviolet #1;vuv#2; and extreme-ultraviolet #1;xuv#2; radiations...;. If the high-frequency comb laser can be generated successfully, there will be a number of applications such as vuv-xuv holography, nanolithography, x-ray atomic clocks, and for the testing of fundamental theories such as quantum electrodynamics. However...
David J. Gross; Washington Taylor
2001-06-04T23:59:59.000Z
We describe projection operators in the matter sector of Witten's cubic string field theory using modes on the right and left halves of the string. These projection operators represent a step towards an analytic solution of the equations of motion of the full string field theory, and can be used to construct Dp-brane solutions of the string field theory when the BRST operator Q is taken to be pure ghost, as suggested in the recent conjecture by Rastelli, Sen and Zwiebach. We show that a family of solutions related to the sliver state are rank one projection operators on the appropriate space of half-string functionals, and we construct higher rank projection operators corresponding to configurations of multiple D-branes.
Appropriating Theory Bonnie Nardi
Nardi, Bonnie
Appropriating Theory Bonnie Nardi forthcoming in D. Sonnenwald, ed. Theory Development in Information: Reflecting on the Process. Austin in this volume concern the development of new theory. I want to take a slightly
On higher spin partition functions
M. Beccaria; A. A. Tseytlin
2015-06-05T23:59:59.000Z
We observe that the partition function of the set of all free massless higher spins s=0,1,2,3,... in flat space is equal to one: the ghost determinants cancel against the "physical" ones or, equivalently, the (regularized) total number of degrees of freedom vanishes. This reflects large underlying gauge symmetry and suggests analogy with supersymmetric or topological theory. The Z=1 property extends also to the AdS background, i.e. the 1-loop vacuum partition function of Vasiliev theory is equal to 1 (assuming a particular regularization of the sum over spins); this was noticed earlier as a consistency requirement for the vectorial AdS/CFT duality. We find that Z=1 is also true in the conformal higher spin theory (with higher-derivative d^{2s} kinetic terms) expanded near flat or conformally flat S^4 background. We also consider the partition function of free conformal theory of symmetric traceless rank s tensor field which has 2-derivative kinetic term but only scalar gauge invariance in flat 4d space. This non-unitary theory has a Weyl-invariant action in curved background and corresponds to "partially massless" field in AdS_5. We discuss in detail the special case of s=2 (or "conformal graviton"), compute the corresponding conformal anomaly coefficients and compare them with previously found expressions for generic representations of conformal group in 4 dimensions.
Mardirossian, Narbe; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu [Department of Chemistry, University of California, Berkeley and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Department of Chemistry, University of California, Berkeley and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2014-05-14T23:59:59.000Z
The limit of accuracy for semi-empirical generalized gradient approximation (GGA) density functionals is explored by parameterizing a variety of local, global hybrid, and range-separated hybrid functionals. The training methodology employed differs from conventional approaches in 2 main ways: (1) Instead of uniformly truncating the exchange, same-spin correlation, and opposite-spin correlation functional inhomogeneity correction factors, all possible fits up to fourth order are considered, and (2) Instead of selecting the optimal functionals based solely on their training set performance, the fits are validated on an independent test set and ranked based on their overall performance on the training and test sets. The 3 different methods of accounting for exchange are trained both with and without dispersion corrections (DFT-D2 and VV10), resulting in a total of 491 508 candidate functionals. For each of the 9 functional classes considered, the results illustrate the trade-off between improved training set performance and diminished transferability. Since all 491 508 functionals are uniformly trained and tested, this methodology allows the relative strengths of each type of functional to be consistently compared and contrasted. The range-separated hybrid GGA functional paired with the VV10 nonlocal correlation functional emerges as the most accurate form for the present training and test sets, which span thermochemical energy differences, reaction barriers, and intermolecular interactions involving lighter main group elements.
Advanced Analysis: Skeleton notes 1. Fourier Theory
Davies, Christopher
Advanced Analysis: Skeleton notes 1. Fourier Theory The Fourier series of a function f() on [-, ] is - anein , where an = an(f) = 1 2 - f()e-in d. The Fourier transform of a function f(x) on R is the function ^f() = 1 2 - f(x)e-ix dx, and the Fourier inversion formula is f(x) = - f()eix d. One circle
Forbus, Kenneth D.
r- ate steam to turn turbines that drive generators. Refriger a- tors rely on essentially the same does) and a separate, teleological reaso n- ing process to map from behavior to function (what the artifact is for). Thus the behaviors of a working turbine include expansion of the working fluid, cooling
Marcos Marino; Pavel Putrov
2012-03-14T23:59:59.000Z
The partition function on the three-sphere of many supersymmetric Chern-Simons-matter theories reduces, by localization, to a matrix model. We develop a new method to study these models in the M-theory limit, but at all orders in the 1/N expansion. The method is based on reformulating the matrix model as the partition function of an ideal Fermi gas with a non-trivial, one-particle quantum Hamiltonian. This new approach leads to a completely elementary derivation of the N^{3/2} behavior for ABJM theory and N=3 quiver Chern-Simons-matter theories. In addition, the full series of 1/N corrections to the original matrix integral can be simply determined by a next-to-leading calculation in the WKB or semiclassical expansion of the quantum gas, and we show that, for several quiver Chern-Simons-matter theories, it is given by an Airy function. This generalizes a recent result of Fuji, Hirano and Moriyama for ABJM theory. It turns out that the semiclassical expansion of the Fermi gas corresponds to a strong coupling expansion in type IIA theory, and it is dual to the genus expansion. This allows us to calculate explicitly non-perturbative effects due to D2-brane instantons in the AdS background.
Quantum Field Theory & Gravity
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Quantum Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664...
BNL | CFN: Theory & Computation
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Theory and Computation Contact: Mark Hybertsen Advances in theory, numerical algorithms and computational capabilities have enabled an unprecedented opportunity for fundamental...
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Dark Matter Theory Dark Matter Theory Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505)...
A Wave-function for Stringy Universes
Costas Kounnas; Nicolaos Toumbas; Jan Troost
2007-07-27T23:59:59.000Z
We define a wave-function for string theory cosmological backgrounds. We give a prescription for computing its norm following an earlier analysis within general relativity. Under Euclidean continuation, the cosmologies we discuss in this paper are described in terms of compact parafermionic worldsheet systems. To define the wave-function we provide a T-fold description of the parafermionic conformal field theory, and of the corresponding string cosmology. In specific examples, we compute the norm of the wave-function and comment on its behavior as a function of moduli.
Interpolating function and Stokes Phenomena
Masazumi Honda; Dileep P. Jatkar
2015-04-28T23:59:59.000Z
When we have two expansions of physical quantity around two different points in parameter space, we can usually construct a family of functions, which interpolates the both expansions. In this paper we study analytic structures of such interpolating functions and discuss their physical implications. We propose that the analytic structures of the interpolating functions provide information on analytic property and Stokes phenomena of the physical quantity, which we approximate by the interpolating functions. We explicitly check our proposal for partition functions of zero-dimensional $\\varphi^4$ theory and Sine-Gordon model. In the zero dimensional Sine-Gordon model, we compare our result with a recent result from resurgence analysis. We also comment on construction of interpolating function in Borel plane.
Interpolating function and Stokes Phenomena
Honda, Masazumi
2015-01-01T23:59:59.000Z
When we have two expansions of physical quantity around two different points in parameter space, we can usually construct a family of functions, which interpolates the both expansions. In this paper we study analytic structures of such interpolating functions and discuss their physical implications. We propose that the analytic structures of the interpolating functions provide information on analytic property and Stokes phenomena of the physical quantity, which we approximate by the interpolating functions. We explicitly check our proposal for partition functions of zero-dimensional $\\varphi^4$ theory and Sine-Gordon model. In the zero dimensional Sine-Gordon model, we compare our result with a recent result from resurgence analysis. We also comment on construction of interpolating function in Borel plane.
Washington Taylor
2006-06-28T23:59:59.000Z
This elementary introduction to string field theory highlights the features and the limitations of this approach to quantum gravity as it is currently understood. String field theory is a formulation of string theory as a field theory in space-time with an infinite number of massive fields. Although existing constructions of string field theory require expanding around a fixed choice of space-time background, the theory is in principle background-independent, in the sense that different backgrounds can be realized as different field configurations in the theory. String field theory is the only string formalism developed so far which, in principle, has the potential to systematically address questions involving multiple asymptotically distinct string backgrounds. Thus, although it is not yet well defined as a quantum theory, string field theory may eventually be helpful for understanding questions related to cosmology in string theory.
Zhang, Shuzhong
Introduction Theory of CAMNS Practical realization of CAMNS Simulation results & Conclusions Blind Separation of Non-negative Sources using Convex Analysis: Theory and Methods Wing-Kin (Ken) Ma Dept Blind Separation of Non-negative Sources using Convex Analysis: Theory and #12;Introduction Theory
Introduction Classical Field Theory
Baer, Christian
Introduction Classical Field Theory Locally Covariant Quantum Field Theory Renormalization Time evolution Conclusions and outlook Locality and Algebraic Structures in Field Theory Klaus Fredenhagen IIÂ¨utsch and Pedro Lauridsen Ribeiro) Klaus Fredenhagen Locality and Algebraic Structures in Field Theory #12
Introduction to Information Theory
Belohlavek, Radim
Introduction to Information Theory and Its Applications Radim BelohlÂ´avek Dept. Computer Science providing introduction to Information Theory. Radim BelohlÂ´avek, Introduction to Information Theory and Its Applications 1 #12;Information Theory: What and Why Â· information: one of key terms in our society
V.3K(1)-Local Homotopy Theory, Iwasawa Theory
V.3K(1)-Local Homotopy Theory, Iwasawa Theory and Algebraic K-Theory Stephen A. Mitchell* 3.3 K(1)-local Homotopy Theory............................................................. 965 -Adic K-Theory ................................................................. 968 K(1)-Localization
Active Oxygen Vacancy Site for Methanol Synthesis from CO2 Hydrogenation on In2O3(110): A DFT Study
Ye, Jingyun; Liu, Changjun; Mei, Donghai; Ge, Qingfeng
2013-06-03T23:59:59.000Z
Methanol synthesis from CO2 hydrogenation on the defective In2O3(110) surface with surface oxygen vacancies has been investigated using periodic density functional theory calculations. The relative stabilities of six possible surface oxygen vacancies numbered from Ov1 to Ov6 on the perfect In2O3(110) surface were examined. The calculated oxygen vacancy formation energies show that the D1 surface with the Ov1 defective site is the most thermodynamically favorable while the D4 surface with the Ov4 defective site is the least stable. Two different methanol synthesis routes from CO2 hydrogenation over both D1 and D4 surfaces were studied and the D4 surface was found to be more favorable for CO2 activation and hydrogenation. On the D4 surface, one of the O atoms of the CO2 molecule fills in the Ov4 site upon adsorption. Hydrogenation of CO2 to HCOO on the D4 surface is both thermodynamically and kinetically favorable. Further hydrogenation of HCOO involves both forming the C-H bond and breaking the C-O bond, resulting in H2CO and hydroxyl. The HCOO hydrogenation is slightly endothermic with an activation barrier of 0.57 eV. A high barrier of 1.14 eV for the hydrogenation of H2CO to H3CO indicates that this step is the rate-limiting step in the methanol synthesis on the defective In2O3(110) surface. We gratefully acknowledge the supports from the National Natural Science Foundation of China (#20990223) and from US Department of Energy, Basic Energy Science program (DE-FG02-05ER46231). D. Mei was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. The computations were performed in part using the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), which is a U.S. Department of Energy national scientific user facility located at Pacific Northwest National Laboratory in Richland, Washington. PNNL is a multiprogram national laboratory operated for DOE by Battelle.
Quantum statistical correlations in thermal field theories: Boundary effective theory
Bessa, A. [Escola de Ciencias e Tecnologia, Universidade Federal do Rio Grande do Norte, Caixa Postal 1524, 59072-970, Natal, RN (Brazil); Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Brandt, F. T. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Carvalho, C. A. A. de; Fraga, E. S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972, Rio de Janeiro, RJ (Brazil)
2010-09-15T23:59:59.000Z
We show that the one-loop effective action at finite temperature for a scalar field with quartic interaction has the same renormalized expression as at zero temperature if written in terms of a certain classical field {phi}{sub c}, and if we trade free propagators at zero temperature for their finite-temperature counterparts. The result follows if we write the partition function as an integral over field eigenstates (boundary fields) of the density matrix element in the functional Schroedinger field representation, and perform a semiclassical expansion in two steps: first, we integrate around the saddle point for fixed boundary fields, which is the classical field {phi}{sub c}, a functional of the boundary fields; then, we perform a saddle-point integration over the boundary fields, whose correlations characterize the thermal properties of the system. This procedure provides a dimensionally reduced effective theory for the thermal system. We calculate the two-point correlation as an example.
ABJ Theory in the Higher Spin Limit
Shinji Hirano; Masazumi Honda; Kazumi Okuyama; Masaki Shigemori
2015-04-27T23:59:59.000Z
We study the conjecture made by Chang, Minwalla, Sharma, and Yin on the duality between the N=6 Vasiliev higher spin theory on AdS_4 and the N=6 Chern-Simons-matter theory, so-called ABJ theory, with gauge group U(N) x U(N+M). Building on our earlier results on the ABJ partition function, we develop the systematic 1/M expansion, corresponding to the weak coupling expansion in the higher spin theory, and compare the leading 1/M correction, with our proposed prescription, to the one-loop free energy of the N=6 Vasiliev theory. We find an agreement between the two sides up to an ambiguity that appears in the bulk one-loop calculation.
Super-renormalizable & Finite Gravitational Theories
Leonardo Modesto; Leslaw Rachwal
2014-07-30T23:59:59.000Z
We hereby introduce and extensively study a class of non-polynomial higher derivative theories of gravity that realize a ultraviolet (UV) completion of Einstein general relativity. These theories are unitary (ghost free) and at most only one-loop divergences survive. The outcome is a class of theories super-renormalizable in even dimension and finite in odd dimension. Moreover, we explicitly prove in D=4 that there exists an extension of the theory that is completely finite and all the beta functions vanish even at one-loop. These results can be easily extended in extra dimensions and it is likely that the higher dimensional theory can be made finite too. Therefore we have the possibility for "finite quantum gravity" in any dimension.
Three approaches to classical thermal field theory
Gozzi, E., E-mail: gozzi@ts.infn.it [Department of Physics, University of Trieste, Strada Costiera 11, Miramare - Grignano, 34151 Trieste (Italy); INFN, Sezione di Trieste (Italy); Penco, R., E-mail: rpenco@syr.edu [Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States)
2011-04-15T23:59:59.000Z
Research Highlights: > Classical thermal field theory admits three equivalent path integral formulations. > Classical Feynman rules can be derived for all three formulations. > Quantum Feynman rules reduce to classical ones at high temperatures. > Classical Feynman rules become much simpler when superfields are introduced. - Abstract: In this paper we study three different functional approaches to classical thermal field theory, which turn out to be the classical counterparts of three well-known different formulations of quantum thermal field theory: the closed-time path (CTP) formalism, the thermofield dynamics (TFD) and the Matsubara approach.
Noncommutative Quantization for Noncommutative Field Theory
Yasumi Abe
2006-07-06T23:59:59.000Z
We present a new procedure for quantizing field theory models on a noncommutative spacetime. The new quantization depends on the noncommutative parameter explicitly and reduces to the canonical quantization in the commutative limit. It is shown that a quantum field theory constructed by the new quantization yeilds exactly the same correlation functions as those of the commutative field theory, that is, the noncommutative effects disappear completely after quantization. This implies, for instance, that by using the new quantization, the noncommutativity can be incorporated in the process of quantization, rahter than in the action as conventionally done.
On higher spin partition functions
Beccaria, M
2015-01-01T23:59:59.000Z
We observe that the partition function of the set of all free massless higher spins s=0,1,2,3,... in flat space is equal to one: the ghost determinants cancel against the "physical" ones or, equivalently, the (regularized) total number of degrees of freedom vanishes. This reflects large underlying gauge symmetry and suggests analogy with supersymmetric or topological theory. The Z=1 property extends also to the AdS background, i.e. the 1-loop vacuum partition function of Vasiliev theory is equal to 1 (assuming a particular regularization of the sum over spins); this was noticed earlier as a consistency requirement for the vectorial AdS/CFT duality. We find that Z=1 is also true in the conformal higher spin theory (with higher-derivative d^{2s} kinetic terms) expanded near flat or conformally flat S^4 background. We also consider the partition function of free conformal theory of symmetric traceless rank s tensor field which has 2-derivative kinetic term but only scalar gauge invariance in flat space. This non...
Non-perturbative beta function in three-dimensional electrodynamics
Ohad Raviv; Yigal Shamir; Benjamin Svetitsky
2014-05-27T23:59:59.000Z
We apply the Schrodinger functional method to the Abelian gauge theory in three dimensions with Nf=2 four-component fermions. We find that the calculated beta function does not cross zero in the range of coupling we study. This implies that the theory exhibits confinement and mass generation, rather than a conformal infared regime.
Fuzzy Functional Dependencies and Lossless Join Decomposition
Parker, Lorraine M.
Recognition]: Models General Terms: Design, Theory Additional Key Words and Phrases: Functional dependencyFuzzy Functional Dependencies and Lossless Join Decomposition of Fuzzy Relational Database Systems with the application of fuzzy logic in a relational database environment with the objective of capturing more meaning
The Theory of Quaternion Matrix Derivatives
Dongpo Xu; Danilo P. Mandic
2014-10-01T23:59:59.000Z
A systematic theory is introduced for calculating the derivatives of quaternion matrix function with respect to quaternion matrix variables. The proposed methodology is equipped with the matrix product rule and chain rule and it is able to handle both analytic and nonanalytic functions. This corrects a flaw in the existing methods, that is, the incorrect use of the traditional product rule. In the framework introduced, the derivatives of quaternion matrix functions can be calculated directly without the differential of this function. Key results are summarized in tables. Several examples show how the quaternion matrix derivatives can be used as an important tool for solving problems related to signal processing.
Green Functions of Relativistic Field Equations
Ying-Qiu Gu
2006-12-20T23:59:59.000Z
In this paper, we restudy the Green function expressions of field equations. We derive the explicit form of the Green functions for the Klein-Gordon equation and Dirac equation, and then estimate the decay rate of the solution to the linear equations. The main motivation of this paper is to show that: (1). The formal solutions of field equations expressed by Green function can be elevated as a postulate for unified field theory. (2). The inescapable decay of the solution of linear equations implies that the whole theory of the matter world should include nonlinear interaction.
Exact results on ABJ theory and the refined topological string
Masazumi Honda; Kazumi Okuyama
2014-07-22T23:59:59.000Z
We study the partition function of the ABJ theory, which is the N=6 superconformal Chern-Simons matter theory with gauge group U(N)xU(N+M) and Chern-Simons levels (k,-k). We exactly compute the ABJ partition function on a three sphere for various k, M and N via the Fermi gas approach. By using these exact data, we show that the ABJ partition function is completely determined by the refined topological string on local P^1 x P^1, including membrane instanton effects in the M-theory dual.
Generalized Quantum Theory and Mathematical Foundations of Quantum Field Theory
Maroun, Michael Anthony
2013-01-01T23:59:59.000Z
The Unique Status of Condensed Matter Theory . . . . . . . .of a Satisfactory Theory . . . . . . . . . . . . BasicThe Generalized Quantum Theory The Postulates and Philosophy
Evolution of the coupling constant in SU(2) lattice gauge theory with two adjoint fermions
Ari J. Hietanen; Kari Rummukainen; Kimmo Tuominen
2009-11-24T23:59:59.000Z
We measure the evolution of the coupling constant using the Schroedinger functional method in the lattice formulation of SU(2) gauge theory with two massless Dirac fermions in the adjoint representation. We observe strong evidence for an infrared fixed point, where the theory becomes conformal. We measure the continuum beta-function and the coupling constant as a function of the energy scale.
Tom Banks
1999-11-10T23:59:59.000Z
This is a series of lectures on M Theory for cosmologists. After summarizing some of the main properties of M Theory and its dualities I show how it can be used to address various fundamental and phenomenological issues in cosmology.
Marciano, W.J.
1984-12-01T23:59:59.000Z
The present state of the art in elementary particle theory is reviewed. Topics include quantum electrodynamics, weak interactions, electroweak unification, quantum chromodynamics, and grand unified theories. 113 references. (WHK)
Covariant Noncommutative Field Theory
Estrada-Jimenez, S. [Licenciaturas en Fisica y en Matematicas, Facultad de Ingenieria, Universidad Autonoma de Chiapas Calle 4a Ote. Nte. 1428, Tuxtla Gutierrez, Chiapas (Mexico); Garcia-Compean, H. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN P.O. Box 14-740, 07000 Mexico D.F., Mexico and Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Monterrey Via del Conocimiento 201, Parque de Investigacion e Innovacion Tecnologica (PIIT) Autopista nueva al Aeropuerto km 9.5, Lote 1, Manzana 29, cp. 66600 Apodaca Nuevo Leon (Mexico); Obregon, O. [Instituto de Fisica de la Universidad de Guanajuato P.O. Box E-143, 37150 Leon Gto. (Mexico); Ramirez, C. [Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Puebla, P.O. Box 1364, 72000 Puebla (Mexico)
2008-07-02T23:59:59.000Z
The covariant approach to noncommutative field and gauge theories is revisited. In the process the formalism is applied to field theories invariant under diffeomorphisms. Local differentiable forms are defined in this context. The lagrangian and hamiltonian formalism is consistently introduced.
Henderson, Leah
2010-01-01T23:59:59.000Z
This thesis consists of three papers on the nature of scientific theories and inference. In many cases, scientific theories can be regarded as organized into hierarchies, with higher levels sometimes called 'paradigms', ...
Galaxy Cosmological Mass Function
Amanda R. Lopes; Alvaro Iribarrem; Marcelo B. Ribeiro; William R. Stoeger
2014-12-03T23:59:59.000Z
We study the galaxy cosmological mass function (GCMF) in a semi-empirical relativistic approach using observational data provided by galaxy redshift surveys. Starting from the theory of Ribeiro & Stoeger (2003, arXiv:astro-ph/0304094) between the mass-to-light ratio, the selection function obtained from the luminosity function (LF) data and the luminosity density, the average luminosity $L$ and the average galactic mass $\\mathcal{M}_g$ are computed in terms of the redshift. $\\mathcal{M}_g$ is also alternatively estimated by a method that uses the galaxy stellar mass function (GSMF). Comparison of these two forms of deriving the average galactic mass allows us to infer a possible bias introduced by the selection criteria of the survey. We used the FORS Deep Field galaxy survey sample of 5558 galaxies in the redshift range $0.5 light ratio and its GSMF data. Assuming ${\\mathcal{M}_{g_0}} \\approx 10^{11} \\mathcal{M}_\\odot$ as the local value of the average galactic mass, the LF approach results in $L_{B} \\propto (1+z)^{(2.40 \\pm 0.03)}$ and $\\mathcal{M}_g \\propto (1+z)^{(1.1\\pm0.2)}$. However, using the GSMF results produces $\\mathcal{M}_g \\propto (1+z)^{(-0.58 \\pm 0.22)}$. We chose the latter result as it is less biased. We then obtained the theoretical quantities of interest, such as the differential number counts, to calculate the GCMF, which can be fitted by a Schechter function. The derived GCMF follows theoretical predictions in which the less massive objects form first, being followed later by more massive ones. In the range $0.5 < z < 2.0$ the GCMF has a strong variation that can be interpreted as a higher rate of galaxy mergers or as a strong evolution in the star formation history of these galaxies.
Theorizing Practice and Practicing Theory
Feldman, Martha S; Orlikowski, Wanda J
2011-01-01T23:59:59.000Z
Practice and Practicing Theory Organization Science 22(5),Practice and Practicing Theory Organization Science 22(5),Practice and Practicing Theory Organization Science 22(5),
Higher Auslander-Reiten Theory
West, Jacob
2015-01-01T23:59:59.000Z
Linearly Com- pact Rings. Applications. , Category Theory,Homology Theory and their Applications II. Lecture Notes in1977), 519– , Representation Theory of Artin Algebras VI: A
Limit theory for overfit models
Calhoun, Grayson Ford
2009-01-01T23:59:59.000Z
theory. . . . . . . . . . . . . . . . . . . . . . . . .1.2 Asymptotic Theory and Main Results . . . . . . . . .Chapter 2 Limit theory for comparing over?t models out-of-
Theory and Modeling of Weakly Bound/Physisorbed Materials
by physisorption: Â CNT, fullerenes, carbon aerogels Â Doping, Decorating, Charging Â· Accuracy of Methods: DFT, QMC CNT may have increased absorption3 Â· Carbon aerogels4 have exhibited 5 wt% for high surface areas, ~1
Variational methods for field theories
Ben-Menahem, S.
1986-09-01T23:59:59.000Z
Four field theory models are studied: Periodic Quantum Electrodynamics (PQED) in (2 + 1) dimensions, free scalar field theory in (1 + 1) dimensions, the Quantum XY model in (1 + 1) dimensions, and the (1 + 1) dimensional Ising model in a transverse magnetic field. The last three parts deal exclusively with variational methods; the PQED part involves mainly the path-integral approach. The PQED calculation results in a better understanding of the connection between electric confinement through monopole screening, and confinement through tunneling between degenerate vacua. This includes a better quantitative agreement for the string tensions in the two approaches. Free field theory is used as a laboratory for a new variational blocking-truncation approximation, in which the high-frequency modes in a block are truncated to wave functions that depend on the slower background modes (Boron-Oppenheimer approximation). This ''adiabatic truncation'' method gives very accurate results for ground-state energy density and correlation functions. Various adiabatic schemes, with one variable kept per site and then two variables per site, are used. For the XY model, several trial wave functions for the ground state are explored, with an emphasis on the periodic Gaussian. A connection is established with the vortex Coulomb gas of the Euclidean path integral approach. The approximations used are taken from the realms of statistical mechanics (mean field approximation, transfer-matrix methods) and of quantum mechanics (iterative blocking schemes). In developing blocking schemes based on continuous variables, problems due to the periodicity of the model were solved. Our results exhibit an order-disorder phase transition. The transfer-matrix method is used to find a good (non-blocking) trial ground state for the Ising model in a transverse magnetic field in (1 + 1) dimensions.
Molecular cavity optomechanics: a theory of plasmon-enhanced Raman scattering
Philippe Roelli; Christophe Galland; Nicolas Piro; Tobias J. Kippenberg
2014-07-06T23:59:59.000Z
The exceptional enhancement of Raman scattering cross-section by localized plasmonic resonances in the near-field of metallic surfaces, nanoparticles or tips has enabled spectrocopic fingerprinting of single-molecules and is widely used in material, chemical and biomedical analysis. Contrasting with this overwhelming practical success, conventional theories based on electromagnetic "hot spots" and electronic or chemical effects cannot account for all experimental observations. Here we present a novel theory of plasmon-enhanced Raman scattering by mapping the problem to cavity optomechanics. Using FEM and DFT simulations we calculate the optomechanical vacuum coupling rate between individual molecules and hot spots of metallic dimers. We find that dynamical backaction of the plasmon on the vibrational mode can lead to amplification of molecular vibrations under blue-detuned laser excitation, thereby revealing an enhancement mechanism not contemplated be- fore. The optomechanical theory provides a quantitative framework for the calculation of enhanced cross-sections, recovers known results, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancement. It yields a new understanding of plasmon-enhanced Raman scattering and opens a route to molecular quantum optomechanics.
Sociology: Computational Organization Theory Sociology: Computational Organization Theory
Sadeh, Norman M.
Sociology: Computational Organization Theory Sociology: Computational Organization Theory Kathleen; organization theory; organizational learning; social networks; expert systems Citation: Kathleen Carley, 1994, "Sociology: Computational Organization Theory." Social Science Computer Review, 12(4): 611-624. #12;Sociology
II.2K-Theory and Intersection Theory
II.2K-Theory and Intersection Theory Henri Gillet 2.1 Introduction.3 K-Theory and Intersection Multiplicities ......................................... 253 Serre's tor Groups .............................................. 259 Higher Rational Equivalence and Milnor K-Theory
Bootstrapping Fuzzy Scalar Field Theory
Christian Saemann
2015-04-13T23:59:59.000Z
We describe a new way of rewriting the partition function of scalar field theory on fuzzy complex projective spaces as a solvable multitrace matrix model. This model is given as a perturbative high-temperature expansion. At each order, we present an explicit analytic expression for most of the arising terms; the remaining terms are computed explicitly up to fourth order. The method presented here can be applied to any model of hermitian matrices. Our results confirm constraints previously derived for the multitrace matrix model by Polychronakos. A further implicit expectation about the shape of the multitrace terms is however shown not to be true.
Introduction to Measurement with Theory
Barnett, William A.; Diewert, W. Erwin; Zellner, Arnold
2009-09-01T23:59:59.000Z
principle. Bennet (1920) and Montgomery (1937) pursued the branch of index number theory where differences replaced the ratios in (12). Thus, they looked for two functions of 4N variables, ?P(p0,p1,q0,q1) and ?Q(p0,p1,q0,q1), which added up...1,q0,q1). However, the basic idea can be traced back to the early accounting and industrial engineering literature; see Harrison (1918; 275). 20 started by Marshall (1890) and Bennet (1920) and continued by Hotelling( 1938; 253- 254), Hicks...
Spin-Statistics Correlations in Various Noncommutative Field Theories
Rahul Srivastava
2013-09-01T23:59:59.000Z
In this thesis we study field theories written on a particular model of noncommutative spacetime, the Groenewold-Moyal (GM) plane. We start with briefly reviewing the novel features of field theories on GM plane e.g. the $\\ast$-product, restoration of Poincar\\'e-Hopf symmetry and twisted commutation relations. We then discuss our work on renormalization of field theories on GM plane. We show that any generic noncommutative theory involving pure matter fields with polynomial interactions, is a renormalizable theory if the analogous commutative theory is renormalizable. We further show that all such noncommutative theories will have same fixed points and $\\beta$-functions for the couplings, as that of the analogous commutative theory. The unique feature of these field theories is the twisted statistics obeyed by the particles. Motivated by it, we look at the possibility of twisted statistics by deforming internal symmetries instead of spacetime symmetries. We construct two different twisted theories which can be viewed as internal symmetry analogue of the GM plane and dipole field theories which arise in the low energy limit of certain string configurations. We further study their various properties like the issue of causality and the scattering formalism. Having studied the mathematical properties of noncommutative and twisted internal symmetries we move on to discuss their potential phenomenological signatures. We first discuss the noncommutative thermal correlation functions and show that because of the twisted statistics, all correlation functions except two-point function get modified. Finally we discuss the modifications in Hanbury-Brown Twiss (HBT) correlation functions due to twisted statistics on GM plane and the potential of observing signatures of noncommutativity by doing a HBT correlation experiment with Ultra High Energy Cosmic Rays (UHECRs).
Modular bootstrap in Liouville field theory
Leszek Hadasz; Zbigniew Jaskolski; Paulina Suchanek
2009-11-22T23:59:59.000Z
The modular matrix for the generic 1-point conformal blocks on the torus is expressed in terms of the fusion matrix for the 4-point blocks on the sphere. The modular invariance of the toric 1-point functions in the Liouville field theory with DOZZ structure constants is proved.
Network Security Validation Using Game Theory
Mavronicolas, Marios
1 Network Security Validation Using Game Theory Vicky Papadopoulou and Andreas Gregoriades Computer.papadopoulou,a.gregoriades}@euc.ac.cy Abstract: Non-functional requirements (NFR) such as network security recently gained widespread attention the immunity property of the distributed systems that depended on these networks. Security requirements
Rigorous results in space-space noncommutative quantum field theory
M. N. Mnatsakanova; Yu. S. Vernov
2006-12-19T23:59:59.000Z
The axiomatic approach based on Wightman functions is developed in noncommutative quantum field theory. We have proved that the main results of the axiomatic approach remain valid if the noncommutativity affects only the spatial variables.
PCT Theorem in Field Theory on Noncommutative Space
Namit Mahajan
2003-07-29T23:59:59.000Z
The PCT theorem is shown to be valid in quantum field theory formulated on noncommutative spacetime by exploiting the properties of the Wightman functions defined in such a set up.
On the excursion theory for linear diffusions Paavo Salminen
Paris-Sud XI, Université de
in the canonical space C of continuous functions : R+ R+. Let Ct := {(s) : s t} denote the smallest -algebra awarded the 1st Gauss prize, by offering some discussion and illustration of K It^o's excursion theory
Theory of light-harvesting in photosynthesis: from structure...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Theory of light-harvesting in photosynthesis: from structure to function May 17, 2011 at 3pm36-428 Thomas Renger Johannes Kepler Universitat -Linz, Austria renger2 abstract In...
Magnetism Theory Group / POSTECH Magnetism Theory Group / POSTECH
Min, Byung Il
Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH J.H . Park et al. #12;'s of FeinCsm e tal The chargeandorbitalordering geom etryin YB a C o 2 O 5 S. K. Kwon etal .Magnetism Theory
Viscosity, Black Holes, and Quantum Field Theory
D. T. Son; A. O. Starinets
2007-07-11T23:59:59.000Z
We review recent progress in applying the AdS/CFT correspondence to finite-temperature field theory. In particular, we show how the hydrodynamic behavior of field theory is reflected in the low-momentum limit of correlation functions computed through a real-time AdS/CFT prescription, which we formulate. We also show how the hydrodynamic modes in field theory correspond to the low-lying quasinormal modes of the AdS black p-brane metric. We provide a proof of the universality of the viscosity/entropy ratio within a class of theories with gravity duals and formulate a viscosity bound conjecture. Possible implications for real systems are mentioned.
Renormalization of Noncommutative Quantum Field Theories
Amilcar R. de Queiroz; Rahul Srivastava; Sachindeo Vaidya
2013-02-14T23:59:59.000Z
We report on a comprehensive analysis of the renormalization of noncommutative \\phi^4 scalar field theories on the Groenewold-Moyal (GM) plane. These scalar field theories are twisted Poincar\\'e invariant. Our main results are that these scalar field theories are renormalizable, free of UV/IR mixing, possess the same fixed points and \\beta-functions for the couplings as their commutative counterparts. We also argue that similar results hold true for any generic noncommutative field theory with polynomial interactions and involving only pure matter fields. A secondary aim of this work is to provide a comprehensive review of different approaches for the computation of the noncommutative S-matrix: noncommutative interaction picture and noncommutative LSZ formalism.
Noncommutative Deformations of Wightman Quantum Field Theories
Harald Grosse; Gandalf Lechner
2008-08-26T23:59:59.000Z
Quantum field theories on noncommutative Minkowski space are studied in a model-independent setting by treating the noncommutativity as a deformation of quantum field theories on commutative space. Starting from an arbitrary Wightman theory, we consider special vacuum representations of its Weyl-Wigner deformed counterpart. In such representations, the effect of the noncommutativity on the basic structures of Wightman theory, in particular the covariance, locality and regularity properties of the fields, the structure of the Wightman functions, and the commutative limit, is analyzed. Despite the nonlocal structure introduced by the noncommutativity, the deformed quantum fields can still be localized in certain wedge-shaped regions, and may therefore be used to compute noncommutative corrections to two-particle S-matrix elements.
Chen, Jiale [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China) [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei (China); Gao, Zhe [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China) [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei (China)
2013-08-15T23:59:59.000Z
The second-order velocity distribution function was calculated from the second-order rf kinetic theory [Jaeger et al., Phys. Plasmas 7, 641 (2000)]. However, the nonresonant ponderomotive force in the radial direction derived from the theory is inconsistent with that from the fluid theory. The inconsistency arises from that the multiple-timescale-separation assumption fails when the second-order Vlasov equation is directly integrated along unperturbed particle orbits. A slowly ramped wave field including an adiabatic turn-on process is applied in the modified kinetic theory in this paper. Since this modification leads only to additional reactive/nonresonant response relevant with the secular resonant response from the previous kinetic theory, the correct nonresonant ponderomotive force can be obtained while all the resonant moments remain unchanged.
$S$-duality in Vafa-Witten theory for non-simply laced gauge groups
Siye Wu
2008-02-14T23:59:59.000Z
Vafa-Witten theory is a twisted N=4 supersymmetric gauge theory whose partition functions are the generating functions of the Euler number of instanton moduli spaces. In this paper, we recall quantum gauge theory with discrete electric and magnetic fluxes and review the main results of Vafa-Witten theory when the gauge group is simply laced. Based on the transformations of theta functions and their appearance in the blow-up formulae, we propose explicit transformations of the partition functions under the Hecke group when the gauge group is non-simply laced. We provide various evidences and consistency checks.
Shear viscosity of the $\\Phi^4$ theory from classical simulation
Homor, M M
2015-01-01T23:59:59.000Z
Shear viscosity of the classical $\\Phi^4$ theory is measured using classical microcanonical simulation. To calculate the Kubo formula, we measure the energy-momentum tensor correlation function, and apply the Green-Kubo relation. Being a classical theory, the results depend on the cutoff which should be chosen in the range of the temperature. Comparison with experimentally accessible systems is also performed.
Shear viscosity of the $?^4$ theory from classical simulation
M. M. Homor; A. Jakovac
2015-05-05T23:59:59.000Z
Shear viscosity of the classical $\\Phi^4$ theory is measured using classical microcanonical simulation. To calculate the Kubo formula, we measure the energy-momentum tensor correlation function, and apply the Green-Kubo relation. Being a classical theory, the results depend on the cutoff which should be chosen in the range of the temperature. Comparison with experimentally accessible systems is also performed.
Fourier Analysis, Distribution Theory, and Wavelets Bengt Ove Turesson1
Nair, M.Thamban
Fourier Analysis, Distribution Theory, and Wavelets Bengt Ove Turesson1 March 13, 2012 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 13 II Fourier Series 14 2 L1 -theory for Fourier Series 15 2.1 Function Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2 Fourier Series and Fourier Coefficients . . . . . . . . . . . . . . . . . 15 2.3 Trigonometric
A Goldstone Theorem in Thermal Relativistic Quantum Field Theory
Christian D. Jaekel; Walter F. Wreszinski
2010-06-01T23:59:59.000Z
We prove a Goldstone Theorem in thermal relativistic quantum field theory, which relates spontaneous symmetry breaking to the rate of space-like decay of the two-point function. The critical rate of fall-off coincides with that of the massless free scalar field theory. Related results and open problems are briefly discussed.
Fractal Strings and Multifractal Zeta Functions
Michel L. Lapidus; Jacques Levy Vehel; John A. Rock
2009-02-09T23:59:59.000Z
For a Borel measure on the unit interval and a sequence of scales that tend to zero, we define a one-parameter family of zeta functions called multifractal zeta functions. These functions are a first attempt to associate a zeta function to certain multifractal measures. However, we primarily show that they associate a new zeta function, the topological zeta function, to a fractal string in order to take into account the topology of its fractal boundary. This expands upon the geometric information garnered by the traditional geometric zeta function of a fractal string in the theory of complex dimensions. In particular, one can distinguish between a fractal string whose boundary is the classical Cantor set, and one whose boundary has a single limit point but has the same sequence of lengths as the complement of the Cantor set. Later work will address related, but somewhat different, approaches to multifractals themselves, via zeta functions, partly motivated by the present paper.
Noncommutative Dipole Field Theories
K. Dasgupta; M. M. Sheikh-Jabbari
2002-02-05T23:59:59.000Z
Assigning an intrinsic constant dipole moment to any field, we present a new kind of associative star product, the dipole star product, which was first introduced in [hep-th/0008030]. We develop the mathematics necessary to study the corresponding noncommutative dipole field theories. These theories are sensible non-local field theories with no IR/UV mixing. In addition we discuss that the Lorentz symmetry in these theories is ``softly'' broken and in some particular cases the CP (and even CPT) violation in these theories may become observable. We show that a non-trivial dipole extension of N=4, D=4 gauge theories can only be obtained if we break the SU(4) R (and hence super)-symmetry. Such noncommutative dipole extensions, which in the maximal supersymmetric cases are N=2 gauge theories with matter, can be embedded in string theory as the theories on D3-branes probing a smooth Taub-NUT space with three form fluxes turned on or alternatively by probing a space with R-symmetry twists. We show the equivalences between the two approaches and also discuss the M-theory realization.
Stretched hydrogen molecule from a constrained-search density-functional perspective
Valone, Steven M [Los Alamos National Laboratory; Levy, Mel [DIKE UNIV.
2009-01-01T23:59:59.000Z
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.
Lucien Hardy
2013-03-06T23:59:59.000Z
We discuss how to reconstruct quantum theory from operational postulates. In particular, the following postulates are consistent only with for classical probability theory and quantum theory. Logical Sharpness: There is a one-to-one map between pure states and maximal effects such that we get unit probability. This maximal effect does not give probability equal to one for any other pure state. Information Locality: A maximal measurement is effected on a composite system if we perform maximal measurements on each of the components. Tomographic Locality: The state of a composite system can be determined from the statistics collected by making measurements on the components. Permutability: There exists a reversible transformation on any system effecting any given permutation of any given maximal set of distinguishable states for that system. Sturdiness: Filters are non-flattening. To single out quantum theory we need only add any requirement that is inconsistent with classical probability theory and consistent with quantum theory.
Automated Lattice Perturbation Theory
Monahan, Christopher
2014-11-01T23:59:59.000Z
I review recent developments in automated lattice perturbation theory. Starting with an overview of lattice perturbation theory, I focus on the three automation packages currently "on the market": HiPPy/HPsrc, Pastor and PhySyCAl. I highlight some recent applications of these methods, particularly in B physics. In the final section I briefly discuss the related, but distinct, approach of numerical stochastic perturbation theory.
Theory Modeling and Simulation
Shlachter, Jack [Los Alamos National Laboratory
2012-08-23T23:59:59.000Z
Los Alamos has a long history in theory, modeling and simulation. We focus on multidisciplinary teams that tackle complex problems. Theory, modeling and simulation are tools to solve problems just like an NMR spectrometer, a gas chromatograph or an electron microscope. Problems should be used to define the theoretical tools needed and not the other way around. Best results occur when theory and experiments are working together in a team.
Covariant Quantum Green's Function for an Accelerated Particle
T. Garavaglia
2001-04-03T23:59:59.000Z
Covariant relativistic quantum theory is used to study the covariant Green's function, which can be used to determine the proper time evolved wave functions that are solutions to the covariant Schr\\"odinger type equation for a massive spin zero particle. The concept of covariant action is used to obtain the Green's function for an accelerated relativistic particle.
Green's Functions and Their Applications to Quantum Mechanics
Morrow, James A.
Green's Functions and Their Applications to Quantum Mechanics Jeff Schueler June 2, 2011 Contents 1 Green's Functions in Quantum Mechanics and Many-body Theory 8 3.1 Time Independent Green's Fuctions . . . . . . . . . . . . . . 8 3.2 Solving the Schr¨odinger Equation Using Green's Functions . . 12 4 Conclusion 13 1 #12
ON GREEN FUNCTIONS ASSOCIATED TO COMPLEX REFLECTION GROUPS
Shoj, Toshiaki
ON GREEN FUNCTIONS ASSOCIATED TO COMPLEX REFLECTION GROUPS TOSHIAKI SHOJI Department of Mathematics Science University of Tokyo Noda, Chiba 2788510, Japan §1. What are the Green functions Green functions are introduced by J.A. Green[G] in 1955, in connection with the representation theory of general linear groups GL
CDF and Survival Function Estimation with Infinite-Order Kernels
Politis, Dimitris N.
) and the survival function is proposed using infinite-order kernels. Fourier transform theory on generalizedCDF and Survival Function Estimation with Infinite-Order Kernels Arthur Berg and Dimitris N sample sizes these estimators can significantly improve the estimation of the CDF and survival function
Density-matrix functionals for pairing in mesoscopic superconductors
Denis Lacroix; Guillaume Hupin
2010-09-03T23:59:59.000Z
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.
Bevir, Mark
2013-01-01T23:59:59.000Z
Trentmann, “The Modern Genealogy of the Consumer: Meanings,2007. Biebricher, T. “Genealogy and Governmentality. ”of Political Theory: The Genealogy of an American Vocation.
Krokhin, Arkadii [Univ. of North Texas, Denton, TX (United States)
2014-04-18T23:59:59.000Z
New applications of the theory of homogenization for heterogeneous metamaterials, in particular for acoustic cloaking and for design and engineering of tunable phononic crystal.
Giulio Bonelli; Kazunobu Maruyoshi; Alessandro Tanzini
2011-12-15T23:59:59.000Z
We study N=2 supersymmetric SU(2) gauge theories coupled to non-Lagrangian superconformal field theories induced by compactifying the six dimensional A_1 (2,0) theory on Riemann surfaces with irregular punctures. These are naturally associated to Hitchin systems with wild ramification whose spectral curves provide the relevant Seiberg-Witten geometries. We propose that the prepotential of these gauge theories on the Omega-background can be obtained from the corresponding irregular conformal blocks on the Riemann surfaces via a generalization of the coherent state construction to the case of higher order singularities.
Constructive Quantum Field Theory
Giovanni Gallavotti
2005-10-04T23:59:59.000Z
A review of the renormalization group approach to the proof of non perturbative ultraviolet stability in scalar field theories in dimension d=2,3.
Long-time limit of correlation functions
Thomas Franosch
2014-07-31T23:59:59.000Z
Auto-correlation functions in an equilibrium stochastic process are well-characterized by Bochner's theorem as Fourier transforms of a finite symmetric Borel measure. The existence of a long-time limit of these correlation functions depends on the spectral properties of the measure. Here we provide conditions applicable to a wide-class of dynamical theories guaranteeing the existence of the long-time limit. We discuss the implications in the context of the mode-coupling theory of the glass transition where a non-trivial long-time limit signals an idealized glass state.
Higgs branch localization of 3d N=2 theories
Masashi Fujitsuka; Masazumi Honda; Yutaka Yoshida
2014-09-17T23:59:59.000Z
We study N=2 supersymmetric gauge theories on squashed 3-sphere and S^1xS^2. Recent studies have shown that the partition functions in a class of N=2 theories have factorized forms in terms of vortex and anti-vortex partition functions by explicitly evaluating matrix integrals obtained from Coulomb branch localization. We directly derive this structure by performing Higgs branch localization. It turns out that more general N=2 theories have this factorization property. We also discuss the factorization of supersymmetric Wilson loop.
Z Theory and its Quantum-Relativistic Operators
Pietro Giorgio Zerbo
2006-02-08T23:59:59.000Z
The view provided by Z theory, based on its quantum-relativistic operators, is an integrated picture of the micro and macro quantities relationships. The axiomatic formulation of the theory is presented in this paper. The theory starts with the existence of the wave function, the existence of three fundamental constants h, c and G as well as the physical quantity Rc (the radius of the space-time continuum) plus the definition of a general form for the quantum-relativistic functional operators. Using such starting point the relationships between relativity, quantum mechanics and cosmological quantities can be clarified.
Generating functionals and Lagrangian partial differential equations
Vankerschaver, Joris; Liao, Cuicui; Leok, Melvin [Department of Mathematics, University of California, San Diego, 9500 Gilman Drive, Dept. 0112, La Jolla, California 92093-0112 (United States)] [Department of Mathematics, University of California, San Diego, 9500 Gilman Drive, Dept. 0112, La Jolla, California 92093-0112 (United States)
2013-08-15T23:59:59.000Z
The main goal of this paper is to derive an alternative characterization of the multisymplectic form formula for classical field theories using the geometry of the space of boundary values. We review the concept of Type-I/II generating functionals defined on the space of boundary data of a Lagrangian field theory. On the Lagrangian side, we define an analogue of Jacobi's solution to the Hamilton–Jacobi equation for field theories, and we show that by taking variational derivatives of this functional, we obtain an isotropic submanifold of the space of Cauchy data, described by the so-called multisymplectic form formula. As an example of the latter, we show that Lorentz's reciprocity principle in electromagnetism is a particular instance of the multisymplectic form formula. We also define a Hamiltonian analogue of Jacobi's solution, and we show that this functional is a Type-II generating functional. We finish the paper by defining a similar framework of generating functions for discrete field theories, and we show that for the linear wave equation, we recover the multisymplectic conservation law of Bridges.
Non-commutative Field Theory with Twistor-like Coordinates
Tomasz R. Taylor
2007-09-16T23:59:59.000Z
We consider quantum field theory in four-dimensional Minkowski spacetime, with the position coordinates represented by twistors instead of the usual world-vectors. Upon imposing canonical commutation relations between twistors and dual twistors, quantum theory of fields described by non-holomorphic functions of twistor variables becomes manifestly non-commutative, with Lorentz symmetry broken by a time-like vector. We discuss the free field propagation and its impact on the short- and long-distance behavior of physical amplitudes in perturbation theory. In the ultraviolet limit, quantum field theories in twistor space are generically less divergent than their commutative counterparts. Furthermore, there is no infrared--ultraviolet mixing problem.
Matrix Quantum Mechanics and Soliton Regularization of Noncommutative Field Theory
Giovanni Landi; Fedele Lizzi; Richard J. Szabo
2004-01-20T23:59:59.000Z
We construct an approximation to field theories on the noncommutative torus based on soliton projections and partial isometries which together form a matrix algebra of functions on the sum of two circles. The matrix quantum mechanics is applied to the perturbative dynamics of scalar field theory, to tachyon dynamics in string field theory, and to the Hamiltonian dynamics of noncommutative gauge theory in two dimensions. We also describe the adiabatic dynamics of solitons on the noncommutative torus and compare various classes of noncommutative solitons on the torus and the plane.
Theory of cargo and membrane trafficking
Lionel Foret; Lutz Brusch; Frank Jülicher
2014-12-03T23:59:59.000Z
Endocytosis underlies many cellular functions including signaling and nutrient uptake. The endocytosed cargo gets redistributed across a dynamic network of endosomes undergoing fusion and fission. Here, a theoretical approach is reviewed which can explain how the microscopic properties of endosome interactions cause the emergent macroscopic properties of cargo trafficking in the endosomal network. Predictions by the theory have been tested experimentally and include the inference of dependencies and parameter values of the microscopic processes. This theory could also be used to infer mechanisms of signal-trafficking crosstalk. It is applicable to in vivo systems since fixed samples at few time points suffice as input data.
Logic and the set theory Lecture 19: The set theory
Choi, Suhyoung
Logic and the set theory Lecture 19: The set theory S. Choi Department of Mathematical Science KAIST, Daejeon, South Korea Fall semester, 2012 S. Choi (KAIST) Logic and set theory November 20, 2012 1 / 24 #12;Introduction About this lecture Axioms of the set theory S. Choi (KAIST) Logic and set theory
Thermal Density Functional Theory in Context Aurora Pribram-Jones,
Burke, Kieron
.3. Consequences 4 III.2.4. Extension to degenerate ground states 4 III.3. Kohn-Sham scheme 5 III.3.1. Exchange [1], and the various methods for modeling it are di- verse [2Â4]. The field includes enormous with useful accuracy. It is important to understand, from the outset, that the logic and methodology of KS
Element orbitals for Kohn-Sham density functional theory
Lin, Lin
2013-01-01T23:59:59.000Z
ranging from 128 atoms to 4394 atoms. ing C and H as sparseranging from 128 atoms to 4394 atoms. The length of thefor 128 atoms to 98.8 a.u. for 4394 atoms. The number of
Mass Spectrometry and Density Functional Theory Characterizations of DNA Modifications
Williams, Renee Therese
2012-01-01T23:59:59.000Z
Containing 1,2-GpG, 1,2-ApG, and 1,3-GpXpG CisplatinODNs) containing a 1,2-GpG, 1,2-ApG, or 1,3-GpXpG cisplatinODNs containing a 1,2-GpG, 1,2-ApG or 1,3-GpXpG intrastrand