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1

Density Functional Theory (DFT) Simulated Annealing (SA)  

E-Print Network (OSTI)

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

2

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

E-Print Network (OSTI)

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

Haule, Kristjan

3

MiniDFT  

NLE Websites -- All DOE Office Websites (Extended Search)

MiniDFT MiniDFT MiniDFT Description MiniDFT is a plane-wave denstity functional theory (DFT) mini-app for modeling materials. Given an set of atomic coordinates and pseudopotentials, MiniDFT computes self-consistent solutions of the Kohn-Sham equations using either the LDA or PBE exchange-correlation functionals. For each iteration of the self-consistent field cycle, 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 kinetic energy is most readily compted ) to real space (where the potential is evaluated ) and back. Davidson diagonalization is used to compute the orbital energies and update the orbital coefficients. The MiniDFT mini-app was excised from the general-purpose Quantum Espresso

4

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

E-Print Network (OSTI)

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

Lindgren, Ingvar

5

Quantum Field Theory & Gravity  

NLE Websites -- All DOE Office Websites (Extended Search)

Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email...

6

First principles DFT study of dye-sensitized CdS quantum dots  

SciTech Connect

Dye-sensitized quantum dots (QDs) are considered promising candidates for dye-sensitized solar cells. In order to maximize their efficiency, detailed theoretical studies are important. Here, we report a first principles density functional theory (DFT) investigation of experimentally realized dye - sensitized QD / ligand systems, viz., Cd{sub 16}S{sub 16}, capped with acetate molecules and a coumarin dye. The hybrid B3LYP functional and a 6?311+G(d,p)/LANL2dz basis set are used to study the geometric, energetic and electronic properties of these clusters. There is significant structural rearrangement in all the clusters studied - on the surface for the bare QD, and in the positions of the acetate / dye ligands for the ligated QDs. The density of states (DOS) of the bare QD shows states in the band gap, which disappear on surface passivation with the acetate molecules. Interestingly, in the dye-sensitised QD, the HOMO is found to be localized mainly on the dye molecule, while the LUMO is on the QD, as required for photo-induced electron injection from the dye to the QD.

Jain, Kalpna; Singh, Kh. S. [Department of Physics, D. J. College, Baraut -250611, U.P. (India); Kishor, Shyam, E-mail: shyam387@gmail.com [Department of Chemistry, J. V. College, Baraut -250611, U.P. (India); Josefesson, Ida; Odelius, Michael [Fysikum, Albanova University Center, Stockholm University, S-106 91 Stockholm (Sweden); Ramaniah, Lavanya M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

2014-04-24T23:59:59.000Z

7

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

SciTech Connect

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

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

2014-05-14T23:59:59.000Z

8

Quantum Decision Theory  

E-Print Network (OSTI)

We argue that, contrary to conventional wisdom, decision theory is not invariant to the physical environment in which a decision is made. Specifically, we show that a decision maker (DM) with access to quantum information resources may be able to do strictly better than a DM with access only to classical information resources. In this respect, our findings are somewhat akin to those in computer science that have established the superiority of quantum over classical algorithms for certain problems. We treat three kinds of decision tree (Kuhn [1950], [1953]): Kuhn trees in which the DM does or does not have perfect recall, and non-Kuhn trees.

Adam Brandenburger; Pierfrancesco La Mura

2011-07-01T23:59:59.000Z

9

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

E-Print Network (OSTI)

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

Botti, Silvana

10

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

E-Print Network (OSTI)

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

Jeremie Messud

2011-11-21T23:59:59.000Z

11

Informational derivation of quantum theory  

SciTech Connect

We derive quantum theory from purely informational principles. Five elementary axioms - causality, perfect distinguishability, ideal compression, local distinguishability, and pure conditioning - define a broad class of theories of information processing that can be regarded as standard. One postulate - purification - singles out quantum theory within this class.

Chiribella, Giulio; D'Ariano, Giacomo Mauro; Perinotti, Paolo [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Ontario, N2L 2Y5 (Canada); QUIT Group, Dipartimento di Fisica ''A. Volta'' and INFN Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy)

2011-07-15T23:59:59.000Z

12

Quantum Probability from Decision Theory?  

E-Print Network (OSTI)

In a recent paper (quant-ph/9906015), Deutsch claims to derive the "probabilistic predictions of quantum theory" from the "non-probabilistic axioms of quantum theory" and the "non-probabilistic part of classical decision theory." We show that his derivation fails because it includes hidden probabilistic assumptions.

H. Barnum; C. M. Caves; J. Finkelstein; C. A. Fuchs; R. Schack

1999-07-07T23:59:59.000Z

13

Quantum probability from decision theory?  

Science Journals Connector (OSTI)

...128. Cox, R. T. 1946 Probability, frequency, and reasonable...Finetti, B. 1972 Theory of probability, vols I and II. Wiley...1999 Quantum theory of probability and decisions. Proc. R...1972 The foundations of statistics. Dover. Von Neumann, J...

2000-01-01T23:59:59.000Z

14

Quantum computation of scattering in scalar quantum field theories  

Science Journals Connector (OSTI)

Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational ... Keywords: quantum algorithm, quantum field theory, simulation

Stephen P. Jordan, Keith S. M. Lee, John Preskill

2014-09-01T23:59:59.000Z

15

Quantum proof systems and entanglement theory  

E-Print Network (OSTI)

Quantum complexity theory is important from the point of view of not only theory of computation but also quantum information theory. In particular, quantum multi-prover interactive proof systems are defined based on ...

Abolfathe Beikidezfuli, Salman

2009-01-01T23:59:59.000Z

16

Quantum Probability from Decision Theory?  

E-Print Network (OSTI)

Deutsch has recently (in quant-ph/9906015) offered a justification, based only on the non-probabilistic axioms of quantum theory and of classical decision theory, for the use of the standard quantum probability rules. In this note, this justification is examined.

J. Finkelstein

1999-07-01T23:59:59.000Z

17

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

E-Print Network (OSTI)

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

Grossman, Jeffrey C.

18

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

E-Print Network (OSTI)

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

Likos, Christos N.

19

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

SciTech Connect

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

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

2014-05-21T23:59:59.000Z

20

Quantum Field Theory in Graphene  

E-Print Network (OSTI)

This is a short non-technical introduction to applications of the Quantum Field Theory methods to graphene. We derive the Dirac model from the tight binding model and describe calculations of the polarization operator (conductivity). Later on, we use this quantity to describe the Quantum Hall Effect, light absorption by graphene, the Faraday effect, and the Casimir interaction.

I. V. Fialkovsky; D. V. Vassilevich

2011-11-13T23:59:59.000Z

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


21

Quantum decision theory as quantum theory of measurement  

E-Print Network (OSTI)

We present a general theory of quantum information processing devices, that can be applied to human decision makers, to atomic multimode registers, or to molecular high-spin registers. Our quantum decision theory is a generalization of the quantum theory of measurement, endowed with an action ring, a prospect lattice and a probability operator measure. The algebra of probability operators plays the role of the algebra of local observables. Because of the composite nature of prospects and of the entangling properties of the probability operators, quantum interference terms appear, which make actions noncommutative and the prospect probabilities non-additive. The theory provides the basis for explaining a variety of paradoxes typical of the application of classical utility theory to real human decision making. The principal advantage of our approach is that it is formulated as a self-consistent mathematical theory, which allows us to explain not just one effect but actually all known paradoxes in human decision making. Being general, the approach can serve as a tool for characterizing quantum information processing by means of atomic, molecular, and condensed-matter systems.

V. I. Yukalov; D. Sornette

2009-03-30T23:59:59.000Z

22

Quantum Theory and Spacelike Measurements  

E-Print Network (OSTI)

Experimentally observed violations of Bell inequalities rule out local realistic theories. Consequently, the quantum state vector becomes a strong candidate for providing an objective picture of reality. However, such an ontological view of quantum theory faces difficulties when spacelike measurements on entangled states have to be described, because time ordering of spacelike events can change under Lorentz-Poincar\\'e transformations. In the present paper it is shown that a necessary condition for consistency is to require state vector reduction on the backward light-cone. A fresh approach to the quantum measurement problem appears feasible within such a framework.

Bernd A. Berg

1998-01-04T23:59:59.000Z

23

Surface Area and Microporosity of a Pillared Interlayered Clay (PILC) from a Hybrid Density Functional Theory (DFT) Method  

Science Journals Connector (OSTI)

Surface Area and Microporosity of a Pillared Interlayered Clay (PILC) from a Hybrid Density Functional Theory (DFT) Method ... Using these models and the experimental isotherm data, the integral equation of adsorption was inverted by a regularization method to yield the micropore and mesopore size distribution of a pillared interlayered clay (PILC). ... In this paper we show how such a deconvolution method can be used for estimating the pore size distribution of a pillared interlayered clay (PILC). ...

James P. Olivier; Mario L. Occelli

2000-12-23T23:59:59.000Z

24

Interference and inequality in quantum decision theory  

E-Print Network (OSTI)

The quantum decision theory is examined in its simplest form of two-condition two-choice setting. A set of inequalities to be satisfied by any quantum conditional probability describing the decision process is derived. Experimental data indicating the breakdown of classical explanations are critically examined with quantum theory using the full set of quantum phases.

Taksu Cheon; Taiki Takahashi

2010-08-16T23:59:59.000Z

25

Indefinite-Metric Quantum Field Theory  

Science Journals Connector (OSTI)

......Umezawa H. Quantum Field Theory (1956) North Holland...Wightman L. Arch. Fysik (1964) 28:129. Y...indefinite-metric quantum field theory, which was published...book, except for some basic points. The use of the...space in quantum field theory has been motivated for......

Noboru Nakanishi

1972-03-01T23:59:59.000Z

26

Quantum Theory of Probability and Decisions  

E-Print Network (OSTI)

The probabilistic predictions of quantum theory are conventionally obtained from a special probabilistic axiom. But that is unnecessary because all the practical consequences of such predictions follow from the remaining, non-probabilistic, axioms of quantum theory, together with the non-probabilistic part of classical decision theory.

David Deutsch

1999-06-04T23:59:59.000Z

27

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

E-Print Network (OSTI)

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

Bjørnstad, Ottar Nordal

28

Processing Information in Quantum Decision Theory  

E-Print Network (OSTI)

A survey is given summarizing the state of the art of describing information processing in Quantum Decision Theory, which has been recently advanced as a novel variant of decision making, based on the mathematical theory of separable Hilbert spaces. This mathematical structure captures the effect of superposition of composite prospects, including many incorporated intended actions. The theory characterizes entangled decision making, non-commutativity of subsequent decisions, and intention interference. The self-consistent procedure of decision making, in the frame of the quantum decision theory, takes into account both the available objective information as well as subjective contextual effects. This quantum approach avoids any paradox typical of classical decision theory. Conditional maximization of entropy, equivalent to the minimization of an information functional, makes it possible to connect the quantum and classical decision theories, showing that the latter is the limit of the former under vanishing interference terms.

V. I. Yukalov; D. Sornette

2008-02-25T23:59:59.000Z

29

From Quantum Mechanics to Quantum Field Theory: The Hopf route  

E-Print Network (OSTI)

From Quantum Mechanics to Quantum Field Theory: The Hopf route A. I. Solomon1 2, G. E. H. Duchamp3. Eliasza-Radzikowskiego 152, PL 31-342 Krak´ow, Poland E-mail: a.i.solomon@open.ac.uk, gduchamp2@free solvable model (at least in the free boson case). On the basis of a combinatorial methodology, we show

Paris-Sud XI, Université de

30

From Quantum Mechanics to Quantum Field Theory: The Hopf route  

E-Print Network (OSTI)

From Quantum Mechanics to Quantum Field Theory: The Hopf route A. I. Solomon 1 2 , G. E. H. Duchamp. Eliasza­Radzikowskiego 152, PL 31­342 Krak??ow, Poland E­mail: a.i.solomon@open.ac.uk, gduchamp2@free solvable model (at least in the free boson case). On the basis of a combinatorial methodology, we show

Recanati, Catherine

31

Quantum-classical correspondence in response theory  

E-Print Network (OSTI)

In this thesis, theoretical analysis of correspondence between classical and quantum dynamics is studied in the context of response theory. Thesis discusses the mathematical origin of time-divergence of classical response ...

Kryvohuz, Maksym

2008-01-01T23:59:59.000Z

32

Quantum Probability and Decision Theory, Revisited  

E-Print Network (OSTI)

An extended analysis is given of the program, originally suggested by Deutsch, of solving the probability problem in the Everett interpretation by means of decision theory. Deutsch's own proof is discussed, and alternatives are presented which are based upon different decision theories and upon Gleason's Theorem. It is argued that decision theory gives Everettians most or all of what they need from `probability'. Some consequences of (Everettian) quantum mechanics for decision theory itself are also discussed.

David Wallace

2002-11-18T23:59:59.000Z

33

Quantum theory from one global symmetry  

E-Print Network (OSTI)

It is shown that unitary quantum theory is not only consistent with but follows from decompositional equivalence: the principle that there is no preferred decomposition of the universe into systems, or alternatively, that there is no preferred quantum reference frame. Decompositional equivalence requires unitary quantum theory to be both observer- and scale-independent, requires time, "systems" and all classical information to be strictly observer-relative, and imposes an unavoidable free-energy cost on the acquisition of observational outcomes. This free energy cost of observation is characterized from first principles and shown to accord with known costs of information acquisition and storage by human observers.

Chris Fields

2014-06-17T23:59:59.000Z

34

http://chem.ps.uci.edu/~kieron/dft/book/ The ABC of DFT  

E-Print Network (OSTI)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 II Basics 55 6 Density functional theory 57 6.1 One electron1 http://chem.ps.uci.edu/~kieron/dft/book/ The ABC of DFT Kieron Burke and friends Department.6 Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2 Functionals 27 2

Burke, Kieron

35

Quantum Theory of Matter: Superfluids & Superconductors  

E-Print Network (OSTI)

. The electrical resistance of a metal decreases when it is cooled. For a superconductor, the resistance vanishes resistance flux expulsion flux quantisation Superfluids atomic Bose condensates liquid helium theory in condensed matter physics elementary excitations in strongly correlated systems 1 Quantum Theory

36

Quantum Theory of Synchroton Radiation  

Science Journals Connector (OSTI)

The classical relativistic expression for the synchrotron radiation spectrum has been generalized to include quantum corrections up to second order in ??/E [1]. The modifications can be traced to the discrete ...

Heimo G. Latal

1979-01-01T23:59:59.000Z

37

Derivation of Quantum Theory from Feynman's Rules  

E-Print Network (OSTI)

Feynman's formulation of quantum theory is remarkable in its combination of formal simplicity and computational power. However, as a formulation of the abstract structure of quantum theory, it is incomplete as it does not account for most of the fundamental mathematical structure of the standard von Neumann-Dirac formalism such as the unitary evolution of quantum states. In this paper, we show how to reconstruct the entirety of the finite-dimensional quantum formalism starting from Feynman's rules with the aid of a single new physical postulate, the no-disturbance postulate. This postulate states that a particular class of measurements have no effect on the outcome probabilities of subsequent measurements performed. We also show how it is possible to derive both the amplitude rule for composite systems of distinguishable subsystems and Dirac's amplitude-action rule, each from a single elementary and natural assumption, by making use of the fact that these assumptions must be consistent with Feynman's rules.

Philip Goyal

2014-03-14T23:59:59.000Z

38

Risk, ambiguity and quantum decision theory  

E-Print Network (OSTI)

In the present article we use the quantum formalism to describe the effects of risk and ambiguity in decision theory. The main idea is that the probabilities in the classic theory of expected utility are estimated probabilities, and thus do not follow the classic laws of probability theory. In particular, we show that it is possible to use consistently the classic expected utility formula, where the probability associated to the events are computed with the equation of quantum interference. Thus we show that the correct utility of a lottery can be simply computed by adding to the classic expected utility a new corrective term, the uncertainty utility, directly connected with the quantum interference term.

Riccardo Franco

2007-11-06T23:59:59.000Z

39

8.324 Quantum Field Theory II, Fall 2002  

E-Print Network (OSTI)

Second semester of a three-semester subject sequence on quantum field theory stressing the relativistic quantum field theories relevant to the physics of the Standard Model. Develops in depth some of the topics discussed ...

Hanany, Amihay

40

Algebras without Involution and Quantum Field Theories  

E-Print Network (OSTI)

Explicit realizations of quantum field theory (QFT) are admitted by a revision to the Wightman axioms for the vacuum expectation values (VEV) of fields. The technical development of QFT is expanded beyond positive functionals on *-algebras while the physically motivated properties: Poincare covariance; positive energy; microcausality; and a Hilbert space realization of states, are preserved.

Glenn Eric Johnson

2014-10-01T23:59:59.000Z

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


41

Magnetic Charge and Quantum Field Theory  

Science Journals Connector (OSTI)

A quantum field theory of magnetic and electric charge is constructed. It is verified to be relativistically invariant in consequence of the charge quantization condition eg?c=n, an integer. This is more restrictive than Dirac's condition, which would also allow half-integral values.

Julian Schwinger

1966-04-29T23:59:59.000Z

42

Natural Philosophy and Quantum Theory  

E-Print Network (OSTI)

We attempt to show how relationalism might help in understanding Bell's theorem. We also present an analogy with Darwinian evolution in order to pedagogically hint at how one might go about using a theory in which one does not even desire to explain correlations by invoking common causes.

Thomas Marlow

2006-08-22T23:59:59.000Z

43

Quantum Cellular Automaton Theory of Light  

E-Print Network (OSTI)

We present a quantum theory of light based on quantum cellular automata (QCA). This approach allows us to have a thorough quantum theory of free electrodynamics encompassing an hypothetical discrete Planck scale. The theory is particularly relevant because it provides predictions at the macroscopic scale that can be experimentally tested. We show how, in the limit of small wave-vector k, the free Maxwell's equations emerge from two Weyl QCAs derived from informational principles in Ref. [1]. Within this framework the photon is introduced as a composite particle made of a pair of correlated massless Fermions, and the usual Bosonic statistics is recovered in the low photon density limit. We derive the main phenomenological features of the theory, consisting in dispersive propagation in vacuum, the occurrence of a small longitudinal polarization, and a saturation effect originated by the Fermionic nature of the photon. We then discuss whether these effects can be experimentally tested, and observe that only the dispersive effects are accessible with current technology, from observations of arrival times of pulses originated at cosmological distances.

Alessandro Bisio; Giacomo Mauro D'Ariano; Paolo Perinotti

2014-07-25T23:59:59.000Z

44

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

SciTech Connect

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

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

2014-05-14T23:59:59.000Z

45

Mathematical Structure of Quantum Decision Theory  

E-Print Network (OSTI)

One of the most complex systems is the human brain whose formalized functioning is characterized by decision theory. We present a "Quantum Decision Theory" of decision making, based on the mathematical theory of separable Hilbert spaces. This mathematical structure captures the effect of superposition of composite prospects, including many incorporated intentions, which allows us to explain a variety of interesting fallacies and anomalies that have been reported to particularize the decision making of real human beings. The theory describes entangled decision making, non-commutativity of subsequent decisions, and intention interference of composite prospects. We demonstrate how the violation of the Savage's sure-thing principle (disjunction effect) can be explained as a result of the interference of intentions, when making decisions under uncertainty. The conjunction fallacy is also explained by the presence of the interference terms. We demonstrate that all known anomalies and paradoxes, documented in the context of classical decision theory, are reducible to just a few mathematical archetypes, all of which finding straightforward explanations in the frame of the developed quantum approach.

V. I. Yukalov; D. Sornette

2008-08-01T23:59:59.000Z

46

No Drama Quantum Theory? A Review  

E-Print Network (OSTI)

Schr\\"{o}dinger (Nature, v.169, 538 (1952)) noted that the complex matter field in the Klein-Gordon equation can be made real by a gauge transform, although charged fields are believed to require complex functions. Surprisingly, the result can be extended to the Dirac equation: three complex components of the Dirac spinor function can be algebraically eliminated, and the remaining component can be made real by a gauge transform. Therefore, the Dirac equation is generally equivalent to one fourth-order partial differential equation for one real function (A. Akhmeteli, J. Math. Phys. v.52, 082303 (2011)). These results both belong in textbooks and can be used for development of new efficient methods of quantum chemistry. The matter field can be algebraically eliminated both in scalar electrodynamics and in spinor electrodynamics in a certain gauge. The resulting equations describe independent dynamics of the electromagnetic field, which permits mathematical simplification and can be useful for interpretation of quantum theory. For example, in the Bohm interpretation, the electromagnetic field can replace the wave function as the guiding field. It is also shown that for these equations, generalized Carleman embedding generates systems of linear equations in the Hilbert space, which look like second-quantized theories and are equivalent to the original nonlinear systems on the set of solutions of the latter. Thus, the relevant local realistic models can be embedded into quantum field theories. These models are equivalent to scalar electrodynamics and spinor electrodynamics, so they correctly describe a large body of experimental data. Although they may need some modifications for better agreement with experiments, they may be of great interest as "no drama quantum theories", as simple (in principle) as classical electrodynamics. Possible issues with the Bell theorem are discussed.

A. Akhmeteli

2011-11-20T23:59:59.000Z

47

Theory of Pseudomodes in Quantum Optical Processes  

E-Print Network (OSTI)

This paper deals with non-Markovian behaviour in atomic systems coupled to a structured reservoir of quantum EM field modes, with particular relevance to atoms interacting with the field in high Q cavities or photonic band gap materials. In cases such as the former, we show that the pseudo mode theory for single quantum reservoir excitations can be obtained by applying the Fano diagonalisation method to a system in which the atomic transitions are coupled to a discrete set of (cavity) quasimodes, which in turn are coupled to a continuum set of (external) quasimodes with slowly varying coupling constants and continuum mode density. Each pseudomode can be identified with a discrete quasimode, which gives structure to the actual reservoir of true modes via the expressions for the equivalent atom-true mode coupling constants. The quasimode theory enables cases of multiple excitation of the reservoir to now be treated via Markovian master equations for the atom-discrete quasimode system. Applications of the theory to one, two and many discrete quasimodes are made. For a simple photonic band gap model, where the reservoir structure is associated with the true mode density rather than the coupling constants, the single quantum excitation case appears to be equivalent to a case with two discrete quasimodes.

B. J. Dalton; S. M. Barnett; B. M. Garraway

2001-02-28T23:59:59.000Z

48

Quantum Electrodynamical Density-Functional Theory: Bridging Quantum Optics and Electronic-Structure Theory  

E-Print Network (OSTI)

In this work we give a comprehensive derivation of an exact and numerically feasible method to perform ab-initio calculations of quantum particles interacting with a quantized electromagnetic field. We present a hierachy of density-functional-type theories that describe the interaction of charged particles with photons and introduce the appropriate Kohn-Sham schemes. We show how the evolution of a system described by quantum electrodynamics in Coulomb gauge is uniquely determined by its initial state and two reduced quantities. These two fundamental observables, the polarization of the Dirac field and the vector potential of the photon field, can be calculated by solving two coupled, non-linear evolution equations without the need to explicitly determine the (numerically infeasible) many-body wave function of the coupled quantum system. To find reliable approximations to the implicit functionals we present the according Kohn-Sham construction. In the non-relativistic limit this density-functional-type theory ...

Ruggenthaler, Michael; Pellegrini, Camilla; Appel, Heiko; Tokatly, Ilya V; Rubio, Angel

2014-01-01T23:59:59.000Z

49

A Foundation Theory of Quantum Mechanics  

E-Print Network (OSTI)

The nRules are empirical regularities that were discovered in macroscopic situations where the outcome is known. When they are projected theoretically into the microscopic domain they predict a novel ontology including the frequent collapse of an atomic wave function, thereby defining an nRule based foundation theory. Future experiments can potentially discriminate between this and other foundation theories of (non-relativistic) quantum mechanics. Important features of the nRules are: (1) they introduce probability through probability current rather than the Born rule, (2) they are valid independent of size (micro or macroscopic), (3) they apply to individual trials, not just to ensembles of trials. (4) they allow all observers to be continuously included in the system without ambiguity, (5) they account for the collapse of the wave function without introducing new or using old physical constants, and (6) in dense environments they provide a high frequency of stochastic localizations of quantum mechanical objects. Key words: measurement, stochastic choice, state reduction.

Richard A Mould

2006-07-10T23:59:59.000Z

50

Nonlinear quantum equations: Classical field theory  

SciTech Connect

An exact classical field theory for nonlinear quantum equations is presented herein. It has been applied recently to a nonlinear Schrdinger equation, and it is shown herein to hold also for a nonlinear generalization of the Klein-Gordon equation. These generalizations were carried by introducing nonlinear terms, characterized by exponents depending on an index q, in such a way that the standard, linear equations, are recovered in the limit q? 1. The main characteristic of this field theory consists on the fact that besides the usual ?(x(vector sign),t), a new field ?(x(vector sign),t) needs to be introduced in the Lagrangian, as well. The field ?(x(vector sign),t), which is defined by means of an additional equation, becomes ?{sup *}(x(vector sign),t) only when q? 1. The solutions for the fields ?(x(vector sign),t) and ?(x(vector sign),t) are found herein, being expressed in terms of a q-plane wave; moreover, both field equations lead to the relation E{sup 2}=p{sup 2}c{sup 2}+m{sup 2}c{sup 4}, for all values of q. The fact that such a classical field theory works well for two very distinct nonlinear quantum equations, namely, the Schrdinger and Klein-Gordon ones, suggests that this procedure should be appropriate for a wider class nonlinear equations. It is shown that the standard global gauge invariance is broken as a consequence of the nonlinearity.

Rego-Monteiro, M. A.; Nobre, F. D. [Centro Brasileiro de Pesquisas Fsicas and National Institute of Science and Technology for Complex Systems, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro - RJ (Brazil)] [Centro Brasileiro de Pesquisas Fsicas and National Institute of Science and Technology for Complex Systems, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro - RJ (Brazil)

2013-10-15T23:59:59.000Z

51

Quantum decoherence in the theory of open systems  

E-Print Network (OSTI)

In the framework of the Lindblad theory for open quantum systems, we determine the degree of quantum decoherence of a harmonic oscillator interacting with a thermal bath. It is found that the system manifests a quantum decoherence which is more and more significant in time. We calculate also the decoherence time scale and analyze the transition from quantum to classical behaviour of the considered system.

A. Isar

2007-04-25T23:59:59.000Z

52

Quantum field theory over F1  

E-Print Network (OSTI)

In this paper we discuss some questions about geometry over the field with one element, motivated by the properties of algebraic varieties that arise in perturbative quantum field theory. We follow the approach to F1-geometry based on torified schemes. We first discuss some simple necessary conditions in terms of Euler characteristic and classes in the Grothendieck ring, then we give a blowup formula for torified varieties and we show that the wonderful compactifications of the graph configuration spaces, that arise in the computation of Feynman integrals in position space, admit an F1-structure. By a similar argument we show that the moduli spaces of curves of genus zero with n marked points admit an F1-structure. We also discuss conditions on hyperplane arrangements, a possible notion of embedded F1-structure and its relation to Chern classes, and questions on Chern classes of varieties with regular torifications.

Dori Bejleri; Matilde Marcolli

2012-09-21T23:59:59.000Z

53

Causality Is Inconsistent With Quantum Field Theory  

SciTech Connect

Causality in quantum field theory means the vanishing of commutators for spacelike separated fields (VCSSF). I will show that VCSSF is not tenable. For VCSSF to be tenable, and therefore, to have both retarded and advanced propagators vanish in the elsewhere, a superposition of negative energy antiparticle and positive energy particle propagators, traveling forward in time, and a superposition of negative energy particle and positive energy antiparticle propagators, traveling backward in time, are required. Hence VCSSF predicts non-vanishing probabilities for both negative energy particles in the forward-through-time direction and positive energy antiparticles in the backwards-through-time direction. Therefore, since VCSSF is unrealizable in a stable universe, tachyonic propagation must occur in denial of causality.

Wolf, Fred Alan [Global Quantum Physics Educational Company, San Francisco CA (United States)

2011-11-29T23:59:59.000Z

54

Construction of relativistic quantum theory: a progress report  

SciTech Connect

We construct the particulate states of quantum physics using a recursive computer program that incorporates non-determinism by means of locally arbitrary choices. Quantum numbers and coupling constants arise from the construction via the unique 4-level combinatorial hierarchy. The construction defines indivisible quantum events with the requisite supraluminal correlations, yet does not allow supraluminal communication. Measurement criteria incorporate c, h-bar and m/sub p/ or (not ''and'') G, connected to laboratory events via finite particle number scattering theory and the counter paradigm. The resulting theory is discrete throughout, contains no infinities, and, as far as we have developed it, is in agreement with quantum mechanical and cosmological fact.

Noyes, H.P.

1986-06-01T23:59:59.000Z

55

Lorentz symmetry breaking as a quantum field theory regulator  

Science Journals Connector (OSTI)

Perturbative expansions of quantum field theories typically lead to ultraviolet (short-distance) divergences requiring regularization and renormalization. Many different regularization techniques have been developed over the years, but most regularizations require severe mutilation of the logical foundations of the theory. In contrast, breaking Lorentz invariance, while it is certainly a radical step, at least does not damage the logical foundations of the theory. I shall explore the features of a Lorentz symmetry breaking regulator in a simple polynomial scalar field theory and discuss its implications. In particular, I shall quantify just how much Lorentz symmetry breaking is required to fully regulate the quantum theory and render it finite. This scalar field theory provides a simple way of understanding many of the key features of Ho?avas recent article [Phys. Rev. D 79, 084008 (2009)] on 3+1 dimensional quantum gravity.

Matt Visser

2009-07-23T23:59:59.000Z

56

Completely Reducible maps in Quantum Information Theory  

E-Print Network (OSTI)

In order to compute the Schmidt decomposition of $A\\in M_k\\otimes M_m$, we must consider an associated self-adjoint map. Here, we show that if $A$ is positive under partial transposition (PPT) or symmetric with positive coefficients (SPC) or invariant under realignment then its associated self-adjoint map is completely reducible. We give applications of this fact in Quantum Information Theory. We recover some theorems recently proved for PPT and SPC matrices and we prove these theorems for matrices invariant under realignment using theorems of Perron-Frobenius theory. One consequence of these theorems is the fact that if $\\mathbb{C}^{k}$ contains $k$ mutually unbiased bases then $\\mathbb{C}^{k}$ contains $k+1$. We search for other types of matrices that could have the same property. We consider a group of linear transformations acting on $M_k\\otimes M_k$, which contains the partial transpositions and the realignment map. For each element of this group, we consider the set of matrices in $M_k\\otimes M_k\\simeq M_{k^2}$ that are positive and remain positive, or invariant, under the action of this element. Within this family of sets, we have the set of PPT matrices, the set of SPC matrices and the set of matrices invariant under realignment. We show that these three sets are the only sets of this family such that the associated self-adjoint map of each matrix is completely reducible. We also show that every matrix invariant under realignment is PPT in $M_2\\otimes M_2$ and we present a counterexample in $M_k\\otimes M_k$, $k\\geq 3$.

Daniel Cariello

2014-12-12T23:59:59.000Z

57

Quantum mechanical effects from deformation theory  

SciTech Connect

We consider deformations of quantum mechanical operators by using the novel construction tool of warped convolutions. The deformation enables us to obtain several quantum mechanical effects where electromagnetic and gravitomagnetic fields play a role. Furthermore, a quantum plane can be defined by using the deformation techniques. This in turn gives an experimentally verifiable effect.

Much, A. [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)] [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)

2014-02-15T23:59:59.000Z

58

Quantum Field Theory on Certain Non-Globally Hyperbolic Spacetimes  

E-Print Network (OSTI)

We study real linear scalar field theory on two simple non-globally hyperbolic spacetimes containing closed timelike curves within the framework proposed by Kay for algebraic quantum field theory on non-globally hyperbolic spacetimes. In this context, a spacetime (M,g) is said to be `F-quantum compatible' with a field theory if it admits a *-algebra of local observables for that theory which satisfies a locality condition known as `F-locality'. Kay's proposal is that, in formulating algebraic quantum field theory on $(M,g)$, F-locality should be imposed as a necessary condition on the *-algebra of observables. The spacetimes studied are the 2- and 4-dimensional spacelike cylinders (Minkowski space quotiented by a timelike translation). Kay has shown that the 4-dimensional spacelike cylinder is F-quantum compatible with massless fields. We prove that it is also F-quantum compatible with massive fields and prove the F-quantum compatibility of the 2-dimensional spacelike cylinder with both massive and massless fields. In each case, F-quantum compatibility is proved by constructing a suitable F-local algebra.

C. J. Fewster; A. Higuchi

1995-08-24T23:59:59.000Z

59

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

SciTech Connect

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

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

2014-04-28T23:59:59.000Z

60

Duality and Braiding in Twisted Quantum Field Theory  

E-Print Network (OSTI)

We re-examine various issues surrounding the definition of twisted quantum field theories on flat noncommutative spaces. We propose an interpretation based on nonlocal commutative field redefinitions which clarifies previously observed properties such as the formal equivalence of Green's functions in the noncommutative and commutative theories, causality, and the absence of UV/IR mixing. We use these fields to define the functional integral formulation of twisted quantum field theory. We exploit techniques from braided tensor algebra to argue that the twisted Fock space states of these free fields obey conventional statistics. We support our claims with a detailed analysis of the modifications induced in the presence of background magnetic fields, which induces additional twists by magnetic translation operators and alters the effective noncommutative geometry seen by the twisted quantum fields. When two such field theories are dual to one another, we demonstrate that only our braided physical states are covariant under the duality.

Mauro Riccardi; Richard J. Szabo

2007-11-09T23:59:59.000Z

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61

Generalized Gravity I : Kinematical Setting and reformalizing Quantum Field Theory  

E-Print Network (OSTI)

The first part of this work deals with the development of a natural differential calculus on non-commutative manifolds. The second part extends the covariance and equivalence principle as well studies its kinematical consequences such as the arising of gauge theory. Furthermore, a manifestly causal and covariant formulation of quantum field theory is presented which surpasses the usual Hamiltonian and path integral construction. A particular representation of this theory on the kinematical structure developed in section three is moreover given.

Johan Noldus

2008-01-28T23:59:59.000Z

62

Maps for general open quantum systems and a theory of linear quantum error correction  

E-Print Network (OSTI)

We show that quantum subdynamics of an open quantum system can always be described by a Hermitian map, irrespective of the form of the initial total system state. Since the theory of quantum error correction was developed based on the assumption of completely positive (CP) maps, we present a generalized theory of linear quantum error correction, which applies to any linear map describing the open system evolution. In the physically relevant setting of Hermitian maps, we show that the CP-map based version of quantum error correction theory applies without modifications. However, we show that a more general scenario is also possible, where the recovery map is Hermitian but not CP. Since non-CP maps have non-positive matrices in their range, we provide a geometric characterization of the positivity domain of general linear maps. In particular, we show that this domain is convex, and that this implies a simple algorithm for finding its boundary.

A. Shabani; D. A. Lidar

2009-02-14T23:59:59.000Z

63

Quantum field theories around a large-Z nucleus  

Science Journals Connector (OSTI)

We analyze quantum electrodynamics around a hypothetical highly charged (Z?137) nucleus by treating it as an external source. In contrast with the foregoing analyses which rely on the one-particle theory we construct a framework which enables us to create the quantum-field-theoretic treatment of the system. To deal with such a nonperturbative question we develop novel truncation and approximation procedures. Keeping only the lowest partial wave of the electron and the photon fields we transcribe the system into the form of two-dimensional fermion theory. We further convert the theory into a two-dimensional boson theory by using a bosonization technique. We then argue that the semiclassical approximation in the resultant boson theory is reasonably good and in particular does take care of the quantum effects of the original fermion theory. We investigate the asymptotic particle state of the theory and find that electrons appear as topological solitons. By analyzing the boson theory with an external source classically we show that the ground state undergoes the phase transition at a certain value of Z (Z?150 for nucleus size ?20 fm) from the normal QED vacuum to an anomalous one which is characterized by the occurrence of real pair creation of electrons and positrons. Our result is confronted with the one obtained by the one-particle-theoretic treatment. Some comments are made on the possibility of understanding the peak structure in positron spectrum observed in heavy-ion collisions.

Yumi Hirata and Hisakazu Minakata

1986-10-15T23:59:59.000Z

64

Neutrino oscillations: Quantum mechanics vs. quantum field theory  

SciTech Connect

A consistent description of neutrino oscillations requires either the quantum-mechanical (QM) wave packet approach or a quantum field theoretic (QFT) treatment. We compare these two approaches to neutrino oscillations and discuss the correspondence between them. In particular, we derive expressions for the QM neutrino wave packets from QFT and relate the free parameters of the QM framework, in particular the effective momentum uncertainty of the neutrino state, to the more fundamental parameters of the QFT approach. We include in our discussion the possibilities that some of the neutrino's interaction partners are not detected, that the neutrino is produced in the decay of an unstable parent particle, and that the overlap of the wave packets of the particles involved in the neutrino production (or detection) process is not maximal. Finally, we demonstrate how the properly normalized oscillation probabilities can be obtained in the QFT framework without an ad hoc normalization procedure employed in the QM approach.

Akhmedov, Evgeny Kh.; Kopp, Joachim; ,

2010-01-01T23:59:59.000Z

65

Quantum kinetic theory with nonlocal coherence  

E-Print Network (OSTI)

In this thesis we develop a novel approximation scheme (eQPA), where the effects of nonlocal coherence are included in the kinetic approach to nonequilibrium quantum dynamics. The key element in our formalism is the finding of new singular shell solutions, located at $k_{0,z} = 0$ in the phase space of 2-point Wightman function, which describe the nonlocal quantum coherence between the ``opposite'' mass-shell excitations for spatially homogeneous and static planar symmetric problems, respectively. This phase space structure leads to a closed set of transport equations for the corresponding on-shell distribution functions $f$, providing an extension to the standard quantum Boltzmann equation. We have considered a number of applications to demonstrate the use of our formalism, including the Klein problem, quantum reflection from a CP-violating mass wall and coherent production of (fermionic and scalar) particles in an oscillating background. Our formalism should be of relevance for many problems in particle physics and cosmology, including baryogenesis and neutrino flavour oscillations in an inhomogeneous background.

Matti Herranen

2009-06-17T23:59:59.000Z

66

Quantum theory of nonequilibrium processes, 1  

SciTech Connect

Green's function techniques for studying nonequilibrium quantum processes are discussed. Perturbation expansions and Green's function equations of motion are developed for noncorrelated and correlated initial states of a system. A transition, from the Kadanoff-Baym Green's function equations of motion to the Boltzmann equation, and specifications of the respective limit, are examined in detail.

Danielewicz, P.

1984-02-01T23:59:59.000Z

67

Comments on Cahill's Quantum Foam Inflow Theory of Gravity  

E-Print Network (OSTI)

We reveal an underlying flaw in Reginald T. Cahill's recently promoted quantum foam inflow theory of gravity. It appears to arise from a confusion of the idea of the Galilean invariance of the acceleration of an individual flow with what is obtained as an acceleration when a homogeneous flow is superposed with an inhomogeneous flow. We also point out that the General Relativistic covering theory he creates by substituting a generalized Painleve-Gullstrand metric into Einstein's field equations leads to absurd results.

T. D. Martin

2004-07-20T23:59:59.000Z

68

Viscosity, Black Holes, and Quantum Field Theory  

E-Print Network (OSTI)

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.

D. T. Son; A. O. Starinets

2007-04-02T23:59:59.000Z

69

Quantum critical benchmark for density functional theory  

E-Print Network (OSTI)

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

Paul E. Grabowski; Kieron Burke

2014-08-09T23:59:59.000Z

70

ETHTH/9926 ON A CLASSICAL LIMIT OF QUANTUM THEORY  

E-Print Network (OSTI)

--8093 Z¨urich, Switzerland 2 Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, NY 10471, USA #12; On a Classical Limit of Quantum Theory . . . , 1 1 GeneralB and ~, and from the speed of light, c, and Newton's law of gravitational attraction he could then infer

71

Tensor networks for Lattice Gauge Theories and Atomic Quantum Simulation  

E-Print Network (OSTI)

We show that gauge invariant quantum link models, Abelian and non-Abelian, can be exactly described in terms of tensor networks states. Quantum link models represent an ideal bridge between high-energy to cold atom physics, as they can be used in cold-atoms in optical lattices to study lattice gauge theories. In this framework, we characterize the phase diagram of a (1+1)-d quantum link version of the Schwinger model in an external classical background electric field: the quantum phase transition from a charge and parity ordered phase with non-zero electric flux to a disordered one with a net zero electric flux configuration is described by the Ising universality class.

E. Rico; T. Pichler; M. Dalmonte; P. Zoller; S. Montangero

2014-06-07T23:59:59.000Z

72

Quantum field theory on a growing lattice  

E-Print Network (OSTI)

We construct the classical and canonically quantized theories of a massless scalar field on a background lattice in which the number of points--and hence the number of modes--may grow in time. To obtain a well-defined theory certain restrictions must be imposed on the lattice. Growth-induced particle creation is studied in a two-dimensional example. The results suggest that local mode birth of this sort injects too much energy into the vacuum to be a viable model of cosmological mode birth.

Brendan Z. Foster; Ted Jacobson

2004-08-06T23:59:59.000Z

73

Kinetic transport theory with quantum coherence  

E-Print Network (OSTI)

We derive transport equations for fermions and bosons in spatially or temporally varying backgrounds with special symmetries, by use of the Schwinger-Keldysh formalism. In a noninteracting theory the coherence information is shown to be encoded in new singular shells for the 2-point function. Imposing this phase space structure to the interacting theory leads to a a self-consistent equation of motion for a physcial density matrix, including coherence and a well defined collision integral. The method is applied e.g. to demonstrate how an initially coherent out-of-equlibrium state approaches equlibrium through decoherence and thermalization.

Matti Herranen; Kimmo Kainulainen; Pyry M. Rahkila

2008-11-06T23:59:59.000Z

74

Quantum Field Theory and Differential Geometry  

E-Print Network (OSTI)

We introduce the historical development and physical idea behind topological Yang-Mills theory and explain how a physical framework describing subatomic physics can be used as a tool to study differential geometry. Further, we emphasize that this phenomenon demonstrates that the interrelation between physics and mathematics have come into a new stage.

W. F. Chen

2008-03-10T23:59:59.000Z

75

Quantum Transition State Theory for proton transfer reactions in enzymes  

E-Print Network (OSTI)

We consider the role of quantum effects in the transfer of hyrogen-like species in enzyme-catalysed reactions. This study is stimulated by claims that the observed magnitude and temperature dependence of kinetic isotope effects imply that quantum tunneling below the energy barrier associated with the transition state significantly enhances the reaction rate in many enzymes. We use a path integral approach which provides a general framework to understand tunneling in a quantum system which interacts with an environment at non-zero temperature. Here the quantum system is the active site of the enzyme and the environment is the surrounding protein and water. Tunneling well below the barrier only occurs for temperatures less than a temperature $T_0$ which is determined by the curvature of potential energy surface near the top of the barrier. We argue that for most enzymes this temperature is less than room temperature. For physically reasonable parameters quantum transition state theory gives a quantitative description of the temperature dependence and magnitude of kinetic isotope effects for two classes of enzymes which have been claimed to exhibit signatures of quantum tunneling. The only quantum effects are those associated with the transition state, both reflection at the barrier top and tunneling just below the barrier. We establish that the friction due to the environment is weak and only slightly modifies the reaction rate. Furthermore, at room temperature and for typical energy barriers environmental degrees of freedom with frequencies much less than 1000 cm$^{-1}$ do not have a significant effect on quantum corrections to the reaction rate.

Jacques P. Bothma; Joel Gilmore; Ross H. McKenzie

2009-10-07T23:59:59.000Z

76

Relative Entropy and Proximity of Quantum Field Theories  

E-Print Network (OSTI)

We study the question of how reliably one can distinguish two quantum field theories (QFTs). Each QFT defines a probability distribution on the space of fields. The relative entropy provides a notion of proximity between these distributions and quantifies the number of measurements required to distinguish between them. In the case of nearby conformal field theories, this reduces to the Zamolodchikov metric on the space of couplings. Our formulation quantifies the information lost under renormalization group flow from the UV to the IR and leads us to a quantification of fine-tuning. This formalism also leads us to a criterion for distinguishability of low energy effective field theories generated by the string theory landscape.

Balasubramanian, Vijay; Maloney, Alexander

2014-01-01T23:59:59.000Z

77

Relative Entropy and Proximity of Quantum Field Theories  

E-Print Network (OSTI)

We study the question of how reliably one can distinguish two quantum field theories (QFTs). Each QFT defines a probability distribution on the space of fields. The relative entropy provides a notion of proximity between these distributions and quantifies the number of measurements required to distinguish between them. In the case of nearby conformal field theories, this reduces to the Zamolodchikov metric on the space of couplings. Our formulation quantifies the information lost under renormalization group flow from the UV to the IR and leads us to a quantification of fine-tuning. This formalism also leads us to a criterion for distinguishability of low energy effective field theories generated by the string theory landscape.

Vijay Balasubramanian; Jonathan J. Heckman; Alexander Maloney

2014-10-24T23:59:59.000Z

78

Microscopic nonequilibrium theory of quantum well solar cells  

Science Journals Connector (OSTI)

We present a microscopic theory of bipolar quantum well structures in the photovoltaic regime, based on the nonequilibrium Greens function formalism for a multiband tight-binding Hamiltonian. The quantum kinetic equations for the single particle Greens functions of electrons and holes are self-consistently coupled to Poissons equation, including intercarrier scattering on the Hartree level. Relaxation and broadening mechanisms are considered by the inclusion of acoustic and optical electron-phonon interaction in a self-consistent Born approximation of the scattering self-energies. Photogeneration of carriers is described on the same level in terms of a self-energy derived from the standard dipole approximation of the electron-photon interaction. Results from a simple two-band model are shown for the local density of states, spectral response, current spectrum, and current-voltage characteristics for generic single quantum well systems.

U. Aeberhard and R. H. Morf

2008-03-28T23:59:59.000Z

79

Quantum tomography meets dynamical systems and bifurcations theory  

SciTech Connect

A powerful tool for studying geometrical problems in Hilbert spaces is developed. We demonstrate the convergence and robustness of our method in every dimension by considering dynamical systems theory. This method provides numerical solutions to hard problems involving many coupled nonlinear equations in low and high dimensions (e.g., quantum tomography problem, existence and classification of Pauli partners, mutually unbiased bases, complex Hadamard matrices, equiangular tight frames, etc.). Additionally, this tool can be used to find analytical solutions and also to implicitly prove the existence of solutions. Here, we develop the theory for the quantum pure state tomography problem in finite dimensions but this approach is straightforwardly extended to the rest of the problems. We prove that solutions are always attractive fixed points of a nonlinear operator explicitly given. As an application, we show that the statistics collected from three random orthonormal bases is enough to reconstruct pure states from experimental (noisy) data in every dimension d ? 32.

Goyeneche, D., E-mail: dardo.goyeneche@cefop.udec.cl [Departamento de Fisca, Universidad de Concepcin, Casilla 160-C, Concepcin, Chile and Center for Optics and Photonics, Universidad de Concepcin, Casilla 4012, Concepcin (Chile); Torre, A. C. de la [Departamento de Fsica, Universidad Nacional de Mar del Plata, IFIMAR-CONICET, Dean Funes 3350, 7600 Mar del Plata (Argentina)

2014-06-15T23:59:59.000Z

80

The Hamilton-Jacobi Theory, Quantum Mechanics and General Relativity  

E-Print Network (OSTI)

The Hamilton-Jacobi theory of Classical Mechanics can be extended in a novel manner to systems which are fuzzy in the sense that they can be represented by wave functions. A constructive interference of the phases of the wave functions then gives us back Classical systems. In a suitable description this includes both Quantum Theory and General Relativity in the well known superspace formulation. However, there are several nuances which provide insight into these latter systems. All this is considered in this paper together with suitable generalization, to cascades of super universes.

B. G. Sidharth

2005-10-12T23:59:59.000Z

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


81

Can we see gravitational collapse in (quantum) gravity perturbation theory?  

E-Print Network (OSTI)

In this paper, by making use of the perturbative expansion around topological field theory we are trying to understand why the standard perturbation theory for General Relativity, which starts with linearized gravity does not see gravitational collapse. We start with investigating classical equations of motion. For zero Immirzi parameter the ambiguity of the standard perturbative expansion is reproduced. This ambiguity is related to the appearance of the linearized diffeomorphism symmetry, which becomes unlinked from the original diffeomorphism symmetry. Introducing Immirzi parameter makes it possible to restore the link between these two symmetries and thus removes the ambiguity, but at the cost of making classical perturbation theory rather intractable. Then we argue that the two main sources of complexity of perturbation theory, infinite number of degrees of freedom and non-trivial curvature of the phase space of General Relativity could be disentangled when studying {\\it quantum} amplitudes. As an illustration we consider zero order approximation in quantum perturbation theory. We identify relevant observables, and sketch their quantization. We find some indications that this zero order approximation might be described by Doubly Special Relativity.

J. Kowalski-Glikman; A. Starodubtsev

2006-12-14T23:59:59.000Z

82

Classical Logical versus Quantum Conceptual Thought: Examples in Economics, Decision theory and Concept Theory  

E-Print Network (OSTI)

Inspired by a quantum mechanical formalism to model concepts and their disjunctions and conjunctions, we put forward in this paper a specific hypothesis. Namely that within human thought two superposed layers can be distinguished: (i) a layer given form by an underlying classical deterministic process, incorporating essentially logical thought and its indeterministic version modeled by classical probability theory; (ii) a layer given form under influence of the totality of the surrounding conceptual landscape, where the different concepts figure as individual entities rather than (logical) combinations of others, with measurable quantities such as 'typicality', 'membership', 'representativeness', 'similarity', 'applicability', 'preference' or 'utility' carrying the influences. We call the process in this second layer 'quantum conceptual thought', which is indeterministic in essence, and contains holistic aspects, but is equally well, although very differently, organized than logical thought. A substantial part of the 'quantum conceptual thought process' can be modeled by quantum mechanical probabilistic and mathematical structures. We consider examples of three specific domains of research where the effects of the presence of quantum conceptual thought and its deviations from classical logical thought have been noticed and studied, i.e. economics, decision theory, and concept theories and which provide experimental evidence for our hypothesis.

Diederik Aerts; Bart D'Hooghe

2008-10-29T23:59:59.000Z

83

Purity of states in the theory of open quantum systems  

E-Print Network (OSTI)

The condition of purity of states for a damped harmonic oscillator is considered in the framework of Lindblad theory for open quantum systems. For a special choice of the environment coefficients, the correlated coherent states are shown to be the only states which remain pure all the time during the evolution of the considered system. These states are also the most stable under evolution in the presence of the environment.

A. Isar

2006-04-28T23:59:59.000Z

84

A New Look at the Position Operator in Quantum Theory  

E-Print Network (OSTI)

The postulate that coordinate and momentum representations are related to each other by the Fourier transform has been accepted from the beginning of quantum theory by analogy with classical electrodynamics. As a consequence, an inevitable effect in standard theory is the wave packet spreading (WPS) of the photon coordinate wave function in directions perpendicular to the photon momentum. This leads to the following paradoxes: if the major part of photons emitted by stars are in wave packet states (what is the most probable scenario) then we should see not separate stars but only an almost continuous background from all stars; no anisotropy of the CMB radiation should be observable; data on gamma-ray bursts, signals from directional radio antennas (in particular, in experiments on Shapiro delay) and signals from pulsars show no signs of WPS. In addition, a problem arises why there are no signs of WPS for protons in the LHC ring. We argue that the above postulate is based neither on strong theoretical arguments nor on experimental data and propose a new consistent definition of the position operator. Then WPS in directions perpendicular to the particle momentum is absent and the paradoxes are resolved. Different components of the new position operator do not commute with each other and, as a consequence, there is no wave function in coordinate representation. Implications of the results for entanglement, quantum locality and the problem of time in quantum theory are discussed.

Felix M. Lev

2015-01-07T23:59:59.000Z

85

A quantum theory of distance along a curve  

E-Print Network (OSTI)

We present a quantum theory of distances along a curve, based on a linear line element that is equal to the operator square root of the quadratic metric of Riemannian geometry. Since the linear line element is an operator, we treat it according to the rules of quantum mechanics and interpret its eigenvalues as physically observable distances; the distance eigenvalues are naturally quantized. There are both positive and negative eigenvalues, which requires interpretation. Multi-element curves are defined as direct sums of line elements, and behave much like systems of spin half electrons in a magnetic field. For a curve of many elements an entropy and energy and temperature are quite naturally defined, leading via standard statistical thermodynamics to a relation between the most probable curve length and temperature. That relation may be viewed as a universal heat-shrinking property of curves. At this stage of the theory we do not include bodies or particles in the mix, do not suggest field equations for the quantum geometry, and questions of interpretation remain. The theory might conceivably be testable using observations of the early Universe, when the temperature of space was presumably quite high. In particular cosmogenesis may be thought of as time stopping at an infinite temperature as we go backwards in time to the beginning.

Ronald J. Adler

2014-02-13T23:59:59.000Z

86

Field Theory for a Deuteron Quantum Liquid  

E-Print Network (OSTI)

Based on general symmetry principles we study an effective Lagrangian for a neutral system of condensed spin-1 deuteron nuclei and electrons, at greater-than-atomic but less-than-nuclear densities. We expect such matter to be present in thin layers within certain low-mass brown dwarfs. It may also be produced in future shock-wave-compression experiments as an effective fuel for laser induced nuclear fusion. We find a background solution of the effective theory describing a net spin zero condensate of deuterons with their spins aligned and anti-aligned in a certain spontaneously emerged preferred direction. The spectrum of low energy collective excitations contains two spin waves with linear dispersions -- like in antiferromagnets -- as well as gapped longitudinal and transverse modes related to the Meissner effect -- like in superconductors. We show that counting of the Nambu-Goldstone modes of spontaneously broken internal and space-time symmetries obeys, in a nontrivial way, the rules of the Goldstone theorem for Lorentz non-invariant systems. We discuss thermodynamic properties of the condensate, and its potential manifestation in the low-mass brown dwarfs.

Lasha Berezhiani; Gregory Gabadadze; David Pirtskhalava

2010-03-03T23:59:59.000Z

87

A connection between quantum decision theory and quantum games: The Hamiltonian of Strategic Interaction  

Science Journals Connector (OSTI)

Abstract Experimental economics and studies in psychology show incompatibilities between human behavior and the perfect rationality assumption which do not fit in classical decision theory, but a more general representation in terms of Hilbert spaces can account for them. This paper integrates previous theoretical works in quantum game theory, Yukalov and Sornettes quantum decision theory and Pothos and Busemeyers quantum cognition model by postulating the Hamiltonian of Strategic Interaction which introduces entanglement in the strategic state of the decision-maker. The Hamiltonian is inherited from the algebraic structure of angular momentum in quantum mechanics and the only required parameter, ? ? ? [ 0 , ? ] , represents the strength of the interaction. We consider it as a non-revealed type of the decision-maker. Considering ? ? to be a continuous random variable, phenomena like learning when participating in repeated games and the influence of the amount of disposable information could be considered as an evolution in the mode and shape of the distribution function f ? ? ( t , I ) . This modeling is motivated by the EisertWilkensLewenstein quantization scheme for Prisoners Dilemma game and then it is applied in the Ultimatum game, which is not a simultaneous but a sequential game. Even when this non-revealed type ? ? cannot be directly observed, we can compute observable outcomes: the probabilities of offering different amounts of coins and the probability of the different offers being accepted or not by the other player.

Ismael Martnez-Martnez

2014-01-01T23:59:59.000Z

88

Decision theory and information propagation in quantum physics  

E-Print Network (OSTI)

In recent papers, Zurek has objected to the decision-theoretic approach of Deutsch and Wallace to deriving the Born rule for quantum probabilities on the grounds that it courts circularity. Deutsch and Wallace assume that the many worlds theory is true and that decoherence gives rise to a preferred basis. However, decoherence arguments use the reduced density matrix, which relies upon the partial trace and hence upon the Born Rule for its validity. Using the Heisenberg Picture and quantum Darwinism - the notion that classical information is quantum information that can proliferate in the environment pioneered by Olliver et al - I show that measurement interactions between two systems only create correlations between a specific set of commuting observables of system 1 and a specific set of commuting observables of system 2. This argument picks out a unique basis in which information flows in the correlations between those sets of commuting observables. I then derive the Born rule for both pure and mixed states and answer some other criticisms of the decision theoretic approach to quantum probability.

Alan Forrester

2006-04-18T23:59:59.000Z

89

Testing axioms for Quantum Mechanics on Probabilistic toy-theories  

E-Print Network (OSTI)

In Ref. [1] one of the authors proposed postulates for axiomatizing Quantum Mechanics as a "fair operational framework", namely regarding the theory as a set of rules that allow the experimenter to predict future events on the basis of suitable tests, having local control and low experimental complexity. In addition to causality, the following postulates have been considered: PFAITH (existence of a pure preparationally faithful state), and FAITHE (existence of a faithful effect). These postulates have exhibited an unexpected theoretical power, excluding all known nonquantum probabilistic theories. Later in Ref. [2] in addition to causality and PFAITH, postulate LDISCR (local discriminability) and PURIFY (purifiability of all states) have been considered, narrowing the probabilistic theory to something very close to Quantum Mechanics. In the present paper we test the above postulates on some nonquantum probabilistic models. The first model, "the two-box world" is an extension of the Popescu-Rohrlich model, which achieves the greatest violation of the CHSH inequality compatible with the no-signaling principle. The second model "the two-clock world" is actually a full class of models, all having a disk as convex set of states for the local system. One of them corresponds to the "the two-rebit world", namely qubits with real Hilbert space. The third model--"the spin-factor"--is a sort of n-dimensional generalization of the clock. Finally the last model is "the classical probabilistic theory". We see how each model violates some of the proposed postulates, when and how teleportation can be achieved, and we analyze other interesting connections between these postulate violations, along with deep relations between the local and the non-local structures of the probabilistic theory.

Giacomo Mauro D'Ariano; Alessandro Tosini

2009-11-29T23:59:59.000Z

90

ORBITAL FUNCTIONALS IN STATIC AND TIME-DEPENDENT DENSITY FUNCTIONAL THEORY  

E-Print Network (OSTI)

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

Gross, E.K.U.

91

Book Review: "Quantum Theory as an Emergent Phenomenon", by Stephen L. Adler  

E-Print Network (OSTI)

This is a book review of the book: "Quantum Theory as an Emergent Phenomenon", by Stephen L. Adler (Cambridge University Press - 2004)

A. Bassi

2005-04-28T23:59:59.000Z

92

Propagation of uncertainties in the nuclear DFT models  

E-Print Network (OSTI)

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.

Markus Kortelainen

2014-09-04T23:59:59.000Z

93

Probabilistic theories: what is special about Quantum Mechanics?  

E-Print Network (OSTI)

Quantum Mechanics (QM) is a very special probabilistic theory, yet we don't know which operational principles make it so. All axiomatization attempts suffer at least one postulate of a mathematical nature. Here I will analyze the possibility of deriving QM as the mathematical representation of a "fair operational framework", i.e. a set of rules which allows the experimenter to make predictions on future "events" on the basis of suitable "tests", e.g. without interference from uncontrollable sources. Two postulates need to be satisfied by any fair operational framework: NSF: "no-signaling from the future"--for the possibility of making predictions on the basis of past tests; PFAITH: "existence of a preparationally faithful state"--for the possibility of preparing any state and calibrating any test. I will show that all theories satisfying NSF admit a C*-algebra representation of events as linear transformations of effects. Based on a very general notion of dynamical independence, it is easy to see that all such probabilistic theories are "non-signaling without interaction" ("non-signaling" for short)--another requirement for a fair operational framework. Postulate PFAITH then implies the "local observability principle", the tensor-product structure for the linear spaces of states and effects, the impossibility of bit commitment and additional features, such an operational definition of transpose, a scalar product for effects, weak-selfduality of the theory, and more. Dual to Postulate PFAITH an analogous postulate for effects would give additional quantum features, such as teleportation. However, all possible consequences of these postulates still need to be investigated, and it is not clear yet if we can derive QM from the present postulates only. [CONTINUES on manuscript

Giacomo Mauro D'Ariano

2008-07-28T23:59:59.000Z

94

Multichannel Quantum Defect Theory of Strontium Rydberg Series  

E-Print Network (OSTI)

Using the reactance matrix approach, we systematically develop new multichannel quantum defect theory models for the singlet and triplet S, P, D and F states of strontium based on improved energy level measurements. The new models reveal additional insights into the character of doubly excited perturber states, and the improved energy level measurements for certain series allow fine structure to be resolved for those series' perturbers. Comparison between the predictions of the new models and those of previous empirical and \\emph{ab initio} studies reveals good agreement with most series, however some discrepancies are highlighted. Using the multichannel quantum defect theory wave functions derived from our models we calculate other observables such as Land\\'e $g_J$-factors and radiative lifetimes. The analysis reveals the impact of perturbers on the Rydberg state properties of divalent atoms, highlighting the importance of including two-electron effects in the calculations of these properties. The work enables future investigations of properties such as Stark maps and long-range interactions of Rydberg states of strontium.

C L Vaillant; M P A Jones; R M Potvliege

2014-02-24T23:59:59.000Z

95

Charges and Generators of Symmetry Transformations in Quantum Field Theory  

Science Journals Connector (OSTI)

Within the Wightman approach to quantum field theory, we review and clarify the properties of formal charges, defined as space integrals for the fourth component of a local current. The conditions for a formal charge to determine an operator (generator) are discussed, in connection with the well-known theorems of Goldstone and of Coleman. The symmetry transformations generated by this operatorgiven its existenceare also studied in some detail. For generators in a scattering theory, we prove their additivity and thus provide a simple way to characterize them from their matrix elements between one-particle states. This characterization allows an immediate construction of the unitary operators implementing the symmetry transformations, and implies that all internal symmetry groups are necessarily compact. We also indicate how to construct interacting fields having definite internal quantum numbers. The present status of the proof of Noether's theorem and of its converse is discussed in the light of the rather delicate properties of formal charges.

CLAUDIO A. ORZALESI

1970-10-01T23:59:59.000Z

96

Causation, decision theory, and Bell's theorem: a quantum analogue of the Newcomb problem  

E-Print Network (OSTI)

I apply some of the lessons from quantum theory, in particular from Bell's theorem, to a debate on the foundations of decision theory and causation. By tracing a formal analogy between the basic assumptions of Causal Decision Theory (CDT)--which was developed partly in response to Newcomb's problem-- and those of a Local Hidden Variable (LHV) theory in the context of quantum mechanics, I show that an agent who acts according to CDT and gives any nonzero credence to some possible causal interpretations underlying quantum phenomena should bet against quantum mechanics in some feasible game scenarios involving entangled systems, no matter what evidence they acquire. As a consequence, either the most accepted version of decision theory is wrong, or it provides a practical distinction, in terms of the prescribed behaviour of rational agents, between some metaphysical hypotheses regarding the causal structure underlying quantum mechanics.

Eric G. Cavalcanti

2009-11-12T23:59:59.000Z

97

Three Dimensional Time Theory: to Unify the Principles of Basic Quantum Physics and Relativity  

E-Print Network (OSTI)

Interpreting quantum mechanics(QM) by classical physics seems like an old topic; And unified theory is in physics frontier; But because the principles of quantum physics and relativity are so different, any theories of trying to unify 4 nature forces should not be considered as completed without truly unifying the basic principles between QM and relativity. This paper will interpret quantum physics by using two extra dimensional time as quantum hidden variables. I'll show that three dimensional time is a bridge to connect basics quantum physics, relativity and string theory. ``Quantum potential'' in Bohm's quantum hidden variable theory is derived from Einstein Lagrangian in 6-dimensional time-space geometry. Statistical effect in the measurement of single particle, non-local properties, de Broglie wave can be naturally derived from the natural properties of three dimensional time. Berry phase, double-slit interference of single particle, uncertainty relation, wave-packet collapse are discussed. The spin and g factor are derived from geometry of extra two time dimensions. Electron can be expressed as time monopole. In the last part of this paper, I'll discuss the relation between three dimensional time and unified theory. Key words: Quantum hidden variable, Interpreting of quantum physics, Berry phase, three dimensional time, unified theory

Xiaodong Chen

2005-10-03T23:59:59.000Z

98

hal00263678, On group theory for quantum gates  

E-Print Network (OSTI)

at the interface of the three pillars: quantum physics, mathematics and computer science. If large-scale quantum of the stabilizer group in terms of maximal normal subgroups [16], sustain the explanation of quantum (de

Paris-Sud XI, Université de

99

Conditional probabilities in quantum theory, and the tunneling time controversy  

E-Print Network (OSTI)

It is argued that there is a sensible way to define conditional probabilities in quantum mechanics, assuming only Bayes's theorem and standard quantum theory. These probabilities are equivalent to the ``weak measurement'' predictions due to Aharonov {\\it et al.}, and hence describe the outcomes of real measurements made on subensembles. In particular, this approach is used to address the question of the history of a particle which has tunnelled across a barrier. A {\\it gedankenexperiment} is presented to demonstrate the physically testable implications of the results of these calculations, along with graphs of the time-evolution of the conditional probability distribution for a tunneling particle and for one undergoing allowed transmission. Numerical results are also presented for the effects of loss in a bandgap medium on transmission and on reflection, as a function of the position of the lossy region; such loss should provide a feasible, though indirect, test of the present conclusions. It is argued that the effects of loss on the pulse {\\it delay time} are related to the imaginary value of the momentum of a tunneling particle, and it is suggested that this might help explain a small discrepancy in an earlier experiment.

Aephraim M. Steinberg

1995-02-02T23:59:59.000Z

100

Quantum theory of optical coherence of nonstationary light in the space-frequency domain  

SciTech Connect

Classical theories of coherence for statistically stationary, as well as, nonstationary optical fields are frequently discussed both in the space-time and in the space-frequency domains. However, the quantum treatment of coherence theory is generally carried out in the space-time domain. In this paper, we present a quantum-mechanical theory of first-order coherence for statistically nonstationary light in the space-frequency domain.

Lahiri, Mayukh [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Wolf, Emil [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

2010-10-15T23:59:59.000Z

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


101

Quantum mechanical analogue of the zeroth law of thermodynamics. (On the problem of incorporating Thermodynamics into Quantum Theory)  

E-Print Network (OSTI)

This approach to the incorporation of stochastic thermodynamics into quantum theory is based on the conception of consistent inclusion of the holistic stochastic environmental influence described by wave functions of the arbitrary vacuum, which was proposed in our paper previously. In this study, we implement the possibility of explicitly incorporating the zeroth law of stochastic thermodynamics in the form of the saturated Schr\\"odinger uncertainty relation into quantum theory. This allows comparatively analyzing the sets of states of arbitrary vacuums, namely, squeezed coherent states (SCSs) and correlated coherent states (CCSs). In addition, we compare the results of the construction of stochastic thermodynamics using SCSs and TCCSs with the versions involving the incorporation of thermodynamics into quantum theory developed previously and based on thermofield dynamics and quantum statistical mechanics.

O. N. Golubjeva; A. D. Sukhanov

2013-03-25T23:59:59.000Z

102

Modeling Excited States in TiO2 Nanoparticles: On the Accuracy of a TD-DFT Based Description  

SciTech Connect

We have investigated the suitability of Time-Dependent Density Functional Theory (TD-DFT) to describe vertical low-energy excitations in naked and hydrated titanium dioxide nanoparticles through a comparison with results from Equation-of-Motion Coupled Cluster (EOM-CC) quantum chemistry methods. We demonstrate that for most TiO2 nanoparticles TD-DFT calculations with commonly used exchange-correlation (XC-)potentials (e.g. B3LYP) and EOM-CC methods give qualitatively similar results. Importantly, however, we also show that for an important subset of structures, TD-DFT gives qualitatively different results depending upon the XC-potential used and that in this case only TD-CAM-B3LYP and TD-BHLYP calculations yield results that are consistent with those obtained using EOM-CC theory. Moreover, we demonstrate that the discrepancies for such structures arise from a particular combination of defects, excitations involving which are charge-transfer excitations and hence are poorly described by XC-potentials that contain no or low fractions of Hartree-Fock like exchange. Finally, we discuss that such defects are readily healed in the presence of ubiquitously present water and that as a result the description of vertical low-energy excitations for hydrated TiO2 nanoparticles is hence non-problematic.

Berardo, Enrico; Hu, Hanshi; Shevlin, S. A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

2014-03-11T23:59:59.000Z

103

Orthogonal-state-based cryptography in quantum mechanics and local post-quantum theories  

E-Print Network (OSTI)

In contrast to the well-known quantum key distribution (QKD) protocols, which encode secret bits in non-orthogonal states, orthogonal-state-based protocols for QKD transmit secret bits deterministically. Even though secure, such a protocol cannot be used to transmit a secret message directly, because an eavesdropper is not prevented from learning something about the direct message before being detected. A quantum secure direct communication (QSDC) scheme satisfies this stronger security requirement. In this work, we study the relationship between security in QKD and QSDC. We show that replacing qubit streaming in a QKD scheme by block-encoding of qubits, we can construct a QSDC scheme. This forms the basis for reducing the security of a QSDC scheme to that of aQKD scheme, in the sense that if the latter is secure, then so is the QSDC scheme built on top of it. We refer to this as \\textit{block reduction}. Further, we show that the security of QKD reduces to that of QSDC, in the sense that if a QSDC protocol is secure, then by sending a random key as the direct message, the corresponding QKD protocol is also secure. This procedure we call as \\textit{key reduction}. Finally, we propose an orthogonal-state-based deterministic key distribution (KD) protocol which is secure in some local post-quantum theories. Its security arises neither from geographic splitting of a code state nor from Heisenberg uncertainty, but from post-measurement disturbance.

S. Arvinda; Anindita Banerjee; Anirban Pathak; R. Srikanth

2014-09-30T23:59:59.000Z

104

Quantum field theory in curved spacetime, the operator product expansion, and dark energy  

E-Print Network (OSTI)

To make sense of quantum field theory in an arbitrary (globally hyperbolic) curved spacetime, the theory must be formulated in a local and covariant manner in terms of locally measureable field observables. Since a generic curved spacetime does not possess symmetries or a unique notion of a vacuum state, the theory also must be formulated in a manner that does not require symmetries or a preferred notion of a ``vacuum state'' and ``particles''. We propose such a formulation of quantum field theory, wherein the operator product expansion (OPE) of the quantum fields is elevated to a fundamental status, and the quantum field theory is viewed as being defined by its OPE. Since the OPE coefficients may be better behaved than any quantities having to do with states, we suggest that it may be possible to perturbatively construct the OPE coefficients--and, thus, the quantum field theory. By contrast, ground/vacuum states--in spacetimes, such as Minkowski spacetime, where they may be defined--cannot vary analytically with the parameters of the theory. We argue that this implies that composite fields may acquire nonvanishing vacuum state expectation values due to nonperturbative effects. We speculate that this could account for the existence of a nonvanishing vacuum expectation value of the stress-energy tensor of a quantum field occurring at a scale much smaller than the natural scales of the theory.

S. Hollands; R. M. Wald

2008-05-22T23:59:59.000Z

105

Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex--Electronic structure,  

E-Print Network (OSTI)

Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex--Electronic structure 2008 Abstract This study presents molecular orbital/density functional theory (MO/DFT) calculations of the electronic structure, vibra- tional frequencies, and equilibrium isotope fractionation factors for iron

Sparks, Donald L.

106

On the Compatibility Between Quantum and Relativistic Effects in an Electromagnetic Bridge Theory  

E-Print Network (OSTI)

The Dipolar Electromagnetic Source (DEMS) model, based on the Poynting Vector Conjecture, conduces in Bridge Theory to a derivation of the Lorentz transformation connecting pairs of events. The results prove a full compatibility between quantum and relativistic effects.

Massimo Auci

2010-03-18T23:59:59.000Z

107

Incompatibility between Self-Observing Consciousness and the Axioms of Quantum theory  

E-Print Network (OSTI)

Based on the standard axioms of quantum theory, we provide a counter-example which invalidates the full compatibility between consciousness and quantum theory. In particular, we present an example of a natural phenomenon in which an observer's the mental state can be fully described in mathematical terms analogous to the state vector that is being observed. This mathematical description of the observer's mental state enables us to examine consciousness within the standard axioms of quantum theory. The separation between the observing party and the physical system being observed, imposed by the axiom of quantum theory, poses a problem when the observer is observing his own mental state, i.e., self-observing consciousness.

Song, Daegene

2007-01-01T23:59:59.000Z

108

Incompatibility between Self-Observing Consciousness and the Axioms of Quantum theory  

E-Print Network (OSTI)

Based on the standard axioms of quantum theory, we provide a counter-example which invalidates the full compatibility between consciousness and quantum theory. In particular, we present an example of a natural phenomenon in which an observer's the mental state can be fully described in mathematical terms analogous to the state vector that is being observed. This mathematical description of the observer's mental state enables us to examine consciousness within the standard axioms of quantum theory. The separation between the observing party and the physical system being observed, imposed by the axiom of quantum theory, poses a problem when the observer is observing his own mental state, i.e., self-observing consciousness.

Daegene Song

2007-06-28T23:59:59.000Z

109

Statistical Separability and the Consistency between Quantum Theory, Relativity and the Causality  

E-Print Network (OSTI)

We show that the non-locality together with the statistical character makes the world statistically separable. The super-luminal signal transmission is impossible. The quantum theory is therefore consistent with the relativity and the causality.

Qi-Ren Zhang

2005-12-19T23:59:59.000Z

110

Quantum field theory solution for a short-range interacting SO(3) quantum spin-glass  

E-Print Network (OSTI)

We study the quenched disordered magnetic system, which is obtained from the 2D SO(3) quantum Heisenberg model, on a square lattice, with nearest neighbors interaction, by taking a Gaussian random distribution of couplings centered in an antiferromagnetic coupling, $\\bar J>0$ and with a width $\\Delta J$. Using coherent spin states we can integrate over the random variables and map the system onto a field theory, which is a generalization of the SO(3) nonlinear sigma model with different flavors corresponding to the replicas, coupling parameter proportional to $\\bar J$ and having a quartic spin interaction proportional to the disorder ($\\Delta J$). After deriving the CP$^1$ version of the system, we perform a calculation of the free energy density in the limit of zero replicas, which fully includes the quantum fluctuations of the CP$^1$ fields $z_i$. We, thereby obtain the phase diagram of the system in terms of ($T, \\bar J, \\Delta J$). This presents an ordered antiferromagnetic (AF) phase, a paramagnetic (PM) phase and a spin-glass (SG) phase. A critical curve separating the PM and SG phases ends at a quantum critical point located between the AF and SG phases, at T=0. The Edwards-Anderson order parameter, as well as the magnetic susceptibilities are explicitly obtained in each of the three phases as a function of the three control parameters. The magnetic susceptibilities show a Curie-type behavior at high temperatures and exhibit a clear cusp, characteristic of the SG transition, at the transition line. The thermodynamic stability of the phases is investigated by a careful analysis of the Hessian matrix of the free energy. We show that all principal minors of the Hessian are positive in the limit of zero replicas, implying in particular that the SG phase is stable.

C. M. S. da Conceio; E. C. Marino

2009-03-02T23:59:59.000Z

111

Generalized Galilean Transformations and the Measurement Problem in the Entropic Dynamics Approach to Quantum Theory  

E-Print Network (OSTI)

Quantum mechanics is an extremely successful and accurate physical theory, yet since its inception, it has been afflicted with numerous conceptual difficulties. The primary subject of this thesis is the theory of entropic quantum dynamics (EQD), which seeks to avoid these conceptual problems by interpreting quantum theory from an informational perspective. We begin by reviewing probability theory as a means of rationally quantifying uncertainties. We then discuss how probabilities can be updated with the method of maximum entropy (ME). We then review some motivating difficulties in quantum mechanics before discussing Caticha's work in deriving quantum theory from the approach of entropic dynamics. After entropic dynamics is introduced, we develop the concepts of symmetries and transformations from an informational perspective. The primary result is the formulation of a symmetry condition that any transformation must satisfy in order to qualify as a symmetry in EQD. We then proceed to apply this condition to the extended Galilean transformation. This transformation is of interest as it exhibits features of both special and general relativity. The transformation yields a gravitational potential that arises from an equivalence of information. We conclude the thesis with a discussion of the measurement problem in quantum mechanics. We discuss the difficulties that arise in the standard quantum mechanical approach to measurement before developing our theory of entropic measurement. In entropic dynamics, position is the only observable. We show how a theory built on this one observable can account for the multitude of measurements present in quantum theory. Furthermore, we show that the Born rule need not be postulated, but can be derived in EQD. Finally, we show how the wave function can be updated by the ME method as the phase is constructed purely in terms of probabilities.

David T. Johnson

2011-05-06T23:59:59.000Z

112

QLib - A Matlab Package for Quantum Information Theory Calculations with Applications  

E-Print Network (OSTI)

Developing intuition about quantum information theory problems is difficult, as is verifying or ruling-out of hypothesis. We present a Matlab package intended to provide the QIT community with a new and powerful tool-set for quantum information theory calculations. The package covers most of the "QI textbook" and includes novel parametrization of quantum objects and a robust optimization mechanism. New ways of re-examining well-known results is demonstrated. QLib is designed to be further developed and enhanced by the community and is available for download at www.qlib.info

Shai Machnes

2007-08-03T23:59:59.000Z

113

Nonlinear eigenvalue problems in Density Functional Theory calculations  

SciTech Connect

Developed in the 1960's by W. Kohn and coauthors, Density Functional Theory (DFT) is a very popular quantum model for First-Principles simulations in chemistry and material sciences. It allows calculations of systems made of hundreds of atoms. Indeed DFT reduces the 3N-dimensional Schroedinger electronic structure problem to the search for a ground state electronic density in 3D. In practice it leads to the search for N electronic wave functions solutions of an energy minimization problem in 3D, or equivalently the solution of an eigenvalue problem with a non-linear operator.

Fattebert, J

2009-08-28T23:59:59.000Z

114

Questions and Answers - How can I explain the Quantum/Wave theory to my  

NLE Websites -- All DOE Office Websites (Extended Search)

What is a meniscus? What is a meniscus? Previous Question (What is a meniscus?) Questions and Answers Main Index Next Question (What is the sun made from?) What is the sun made from? How can I explain the Quantum/Wave theory to my class? You can't! The folks who have postulated the quantum nature of matter and wave-particle duality, and other quantum theories have trouble explaining it in terms other than mathematical equations. When trying to explain it in conceptual terms, we're asked to accept things that don't make sense, and in some ways, physicists use this as justification that the theory is correct. Anyway, here are a couple ideas for discussing the quantum/wave properties of energy. Until around 1900, when Max Planck developed the idea of quanta, energy had been thought to be a phenomenon of continuous flow - basically waves.

115

The Formulation of Quantum Field Theory with no Renormalization of Masses and Coupling Constants of Fermions  

E-Print Network (OSTI)

The paper presents the formulation of quantum field theory without renormalization of masses and coupling constants of fermions. Counter-terms, compensating for divergent quantities in self-energy diagrams of fermions and vacuum polarization diagrams at all orders of the perturbation theory, appear in the appropriate Hamiltonians under the special time-dependent unitary transformation.

Neznamov, V P

2015-01-01T23:59:59.000Z

116

Theory of Coulomb-blockade oscillations in the conductance of a quantum dot  

Science Journals Connector (OSTI)

A linear-response theory is developed for resonant tunneling through a quantum dot of small capacitance, in the regime of thermally broadened resonances. The theory extends the classical theory of Coulomb-blockade oscillations by Kulik and Shekhter to the resonant-tunneling regime. Both the cases of negligible and strong inelastic scattering in the quantum dot are considered. Effects from the non-Fermi-Dirac distribution of electrons among the energy levels (occurring when kT is comparable to the level separation) are fully included. Explicit analytic results are obtained for the periodicity, amplitude, line shape, and activation energy of the conductance oscillations.

C. W. J. Beenakker

1991-07-15T23:59:59.000Z

117

Quantum Mechanics, Group Theory, and C60 Frank Rioux  

E-Print Network (OSTI)

production in macroscopic amounts2 has generated a tremendous amount of research activity in chemistry and the angular momentum quantum number. (1) Just as the quantum mechanical solution for the one-electron hydrogen all other levels are completely filled. Using traditional group theoretical methods6 , it can be shown that

Rioux, Frank

118

Multiscale quantum-defect theory and its application to atomic spectrum  

E-Print Network (OSTI)

We present a multiscale quantum-defect theory based on the first analytic solution for a two-scale long range potential consisting of a Coulomb potential and a polarization potential. In its application to atomic structure, the theory extends the systematic understanding of atomic Rydberg states, as afforded by the standard single-scale quantum-defect theory, to a much greater range of energies to include the first few excited states and even the ground state. Such a level of understanding has important implications not only on atomic structure, but also on the electronic structure of molecules and on atomic and molecular interactions and reactions. We demonstrate the theory by showing that it provides an analytic description of the energy variations of the standard Coulomb quantum defects for alkali-metal atoms.

Fu, Haixiang; Tey, Meng Khoon; You, Li; Gao, Bo

2015-01-01T23:59:59.000Z

119

Quantum theory of nonequilibrium processes II. Application to nuclear collisions  

SciTech Connect

In the high-energy (E/sub lab/> or =200 MeV/nucl) heavy ion-collisions, the quantum uncertainty of nucleon energies, given by the collision frequency, is of the order of (50-100) MeV. At hundreds MeV/nucl beam energies, the uncertainty is comparable with nucleon energies in the equal ion-velocity frame, indicating a quantum character of the dynamics. The quantum dynamics of a collision process is examined using nonequilibrium Green's function methods. Numerical calculations of collisions in an interpenetrating nuclear matter model, at the energy E/sub lab/ = 400 MeV/nucl, are performed. Comparison of the quantum dynamics, with the classical Markovian dynamics from the Boltzmann equation, reveals effects of the ill-defined nucleon energies in the nucleon momentum distribution. It is shown that the quantum dynamics proceeds twice as slow as Boltzmann dynamics, but the off-shell kinematics compensates for this somewhat.

Danielewicz, P.

1984-02-01T23:59:59.000Z

120

Pascual Jordan's legacy and the ongoing research in quantum field theory  

E-Print Network (OSTI)

Pascual Jordan's path-breaking role as the protagonist of quantum field theory (QFT) is recalled and his friendly dispute with Dirac's particle-based relativistic quantum theory is presented as the start of the field-particle conundrum which, though in modified form, persists up to this date. Jordan had an intuitive understanding that the existence of a causal propagation with finite propagation speed in a quantum theory led to radically different physical phenomena than those of QM. The conceptional-mathematical understanding for such an approach began to emerge only 30 years later. The strongest link between Jordan's view of QFT and modern "local quantum physics" is the central role of causal locality as the defining principle of QFT as opposed to the Born localization in QM. The issue of causal localization is also the arena where misunderstandings led to a serious derailment of large part of particle theory e.g. the misinterpretation of an infinite component pointlike field resulting from the quantization of the Nambu-Goto Lagrangian as a spacetime quantum string. The new concept of modular localization, which replaces Jordan's causal locality, is especially important to overcome the imperfections of gauge theories for which Jordan was the first to note nonlocal aspects of physical (not Lagrangian) charged fields. Two interesting subjects in which Jordan was far ahead of his contemporaries will be presented in two separate sections.

Bert Schroer

2010-10-21T23:59:59.000Z

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


121

Green function identities in Euclidean quantum field theory  

E-Print Network (OSTI)

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.

G. Sardanashvily

2006-04-01T23:59:59.000Z

122

Theory and proposal for a quantum-degenerate electron source  

E-Print Network (OSTI)

for a quantum-degenerate electron source M. Zolotorev, E. D.propose a pulsed electron source capable of a 6D brightnesspropose a pulsed electron source with brightness approaching

Zolotorev, Max; Commins, Eugene D.; Sannibale Fernando

2006-01-01T23:59:59.000Z

123

Quantum Field and Cosmic Field-Finite Geometrical Field Theory of Matter Motion Part Three  

E-Print Network (OSTI)

This research establishes an operational measurement way to express the quantum field theory in a geometrical form. In four-dimensional spacetime continuum, the orthogonal rotation is defined. It forms two sets of equations: one set is geometrical equations, another set is the motion equations. The Lorentz transformation can be directly derived from the geometrical equations, and the proper time of general relativity is well expressed by time displacement field. By the motion equations, the typical time displacement field of matter motion is discussed. The research shows that the quantum field theory can be established based on the concept of orthogonal rotation. On this sense, the quantum matter motion in physics is viewed as the orthogonal rotation of spacetime continuum. In this paper, it shows that there are three typical quantum solutions. One is particle-like solution, one is generation-type solution, and one is pure wave type solution. For each typical solution, the force fields are different. Many fea...

Xiao, J

2005-01-01T23:59:59.000Z

124

Necessary and sufficient condition for a realistic theory of quantum systems  

E-Print Network (OSTI)

We study the possibility to describe pure quantum states and evens with classical probability distributions and conditional probabilities and show that the distributions and/or conditional probabilities have to assume negative values, except for a simple model whose realistic space dimension is not smaller than the Hilbert space dimension of the quantum system. This gives a negative answer to a question proposed by Montina [Phys.Rev.Lett.{\\bf 97}, 180401 (2006)] whether or not does there exist a classical theory whose phase-space dimension is much smaller than the Hilbert space dimension for any quantum system. Thus, any realistic theory of quantum mechanics with nonnegative probability distributions and conditional probabilities requires a number of variables grows exponentially with the physical size.

Zeqian Chen

2009-11-13T23:59:59.000Z

125

Detailed discussions and calculations of quantum Regge calculus of Einstein-Cartan theory  

Science Journals Connector (OSTI)

This article presents detailed discussions and calculations of the recent paper Quantum Regge calculus of Einstein-Cartan theory in 9. The Euclidean space-time is discretized by a four-dimensional simplicial complex. We adopt basic tetrad and spin-connection fields to describe the simplicial complex. By introducing diffeomorphism and local Lorentz invariant holonomy fields, we construct a regularized Einstein-Cartan theory for studying the quantum dynamics of the simplicial complex and fermion fields. This regularized Einstein-Cartan action is shown to properly approach to its continuum counterpart in the continuum limit. Based on the local Lorentz invariance, we derive the dynamical equations satisfied by invariant holonomy fields. In the mean-field approximation, we show that the averaged size of 4-simplex, the element of the simplicial complex, is larger than the Planck length. This formulation provides a theoretical framework for analytical calculations and numerical simulations to study the quantum Einstein-Cartan theory.

She-Sheng Xue

2010-09-30T23:59:59.000Z

126

Density Functional Theory (DFT) Rob Parrish  

E-Print Network (OSTI)

: ­ Nuclear-electron attraction (exact) ­ Classical Coulomb electron repulsion (exact) ­ Dynamical correlation ­ Nondynamical correlation ­ Dispersion 8 Dealbreaker! (Almost) #12;Breakthrough: The Kohn-Sham Witchcraft) Center Nucleus (k=3, naïve) Plots are of nuclear weights, wn. Black stars represent nuclear positions. 16

Sherrill, David

127

Non-equilibrium Quantum Many-Body Green Function Formalism in the light of Quantum Information Theory  

E-Print Network (OSTI)

The following issues are discussed inspired by the recent paper of Kadanoff (arXiv: 1403:6162): (a) Construction of a generalized one-particle Wigner distribution (GWD) function (analog of the classical distribution function) from which the quantum kinetic equation due to Kadanoff and Baym (KB) is derived, often called the Quantum Boltzmann Equation (QBE); (b) The equation obeyed by this has a collision contribution in the form of a two-particle Green function. This term is manipulated to have Kinetic Entropy in parallel to its counterpart in the classical Boltzmann kinetic equation for the classical distribution function. This proved to be problematic in that unlike in the classical Boltzmann kinetic equation, the contribution from the kinetic entropy term was non-positive; (3) Kadanoff surmised that this situation could perhaps be related to quantum entanglement that may not have been included in his theory. It is shown that GWD is not positive everywhere (indicating dynamical quantumness) just like the commonly recognized property of the Wigner function (negative property indicating quantumness of the state). The issue of non-positive feature appearing in approximate evaluation of patently positive entities in many particle systems is here pointed to an early discussion of this issue (Phys. Rev. A10, 1852 (1974)) in terms of a theorem on truncation of cumulant expansion of a probability distribution function due to Marcinkeiwicz. The last issue of presence or absence of entanglement in an approximate evaluation of a many particle correlation poses a new problem; it is considered here in terms of fermionic entanglement theory in the light of density matrix and Green function theory of many-fermion systems. The clue comes from the fact that the Hartree-Fock approximation exhbits no entantanglement in two-particle fermion density matrix and hence also in two-particle Green function.

A. K. Rajgaopal

2014-05-12T23:59:59.000Z

128

Quantum-Gravity Phenomenology and the DSR Ether Theories  

E-Print Network (OSTI)

Guided primarily by versions of a theoretical framework called Doubly Special Relativity, or DSR, that are supposed to entail speeds of light that vary with energy while preserving the relativity of inertial frames, quantum-gravity phenomenologists have recently been seeking clues to quantum gravity, in hoped-for differing times of arrival, for light of differing energies, from cosmologically distant sources. However, it has long been known that signals, of arbitrarily high speed in opposing directions, could be used to observe the translational state of (absolute) rest, as could signals of a fixed speed different from c. Consequently, the above versions of DSR are nonviable.

Kenneth M. Sasaki

2010-09-20T23:59:59.000Z

129

Spin Matrix Theory: A quantum mechanical model of the AdS/CFT correspondence  

E-Print Network (OSTI)

We introduce a new quantum mechanical theory called Spin Matrix theory (SMT). The theory is interacting with a single coupling constant g and is based on a Hilbert space of harmonic oscillators with a spin index taking values in a Lie algebra representation as well as matrix indices for the adjoint representation of U(N). We show that SMT describes N=4 super-Yang-Mills theory (SYM) near zero-temperature critical points in the grand canonical phase diagram. Equivalently, SMT arises from non-relativistic limits of N=4 SYM. Even though SMT is a non-relativistic quantum mechanical theory it contains a variety of phases mimicking the AdS/CFT correspondence. Moreover, the infinite g limit of SMT can be mapped to the supersymmetric sector of string theory on AdS_5 x S^5. We study SU(2) SMT in detail. At large N and low temperatures it is a theory of spin chains that for small g resembles planar gauge theory and for large g a non-relativistic string theory. When raising the temperature a partial deconfinement transit...

Harmark, Troels

2014-01-01T23:59:59.000Z

130

Density Functional Theory for Superconductors  

E-Print Network (OSTI)

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

Gross, E.K.U.

131

Density Functional Theory Approach to Nuclear Fission  

E-Print Network (OSTI)

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

N. Schunck

2013-01-20T23:59:59.000Z

132

Density functional theory (DFT) and ab initio molecular orbital calculations have been employed to determine the structures and energies of the isomers of the OH-toluene adduct, the methyl hydroxycyclohexadienyl radical, and their corresponding transitio  

NLE Websites -- All DOE Office Websites (Extended Search)

Laboratory Investigation of Organic Aerosol Formation from Aromatic Hydrocarbons (DOE Award No. DE-FG02-02ER63098) Prepared by Luisa T. Molina, Renyi Zhang and Mario J. Molina Our work for this DOE funded project includes: (1) measurements of the kinetics and mechanism of the gas-phase oxidation reactions of the aromatic hydrocarbons initiated by OH; (2) measurements of aerosol formation from the aromatic hydrocarbons; and (3) theoretical studies to elucidate the OH-toluene reaction mechanism using quantum-chemical and rate theories. (1) Measurements of Gas-Phase Kinetics and Mechanism Work has been accomplished to develop laboratory instrumentation to conduct kinetic and mechanistic measurements of the aromatic hydrocarbon reactions initiated by OH, using

133

Theory of indirect exciton photoluminescence in elevated quantum trap  

Science Journals Connector (OSTI)

Abstract Inspired by an experiment of indirect excitons photoluminescence (PL) in elevated quantum trap (High et al., 2009), we theoretically investigate the energy relaxation and nonlinear interactions of indirect excitons in coupled quantum wells. It is shown that, when increasing the laser power, the intensity reversion of two PL peaks is due to the phonon necklace effect. In addition, we use a nonlinear Schrdinger equation including attractive two-body, repulsive three-body interactions and the excitation power dependence of energy distribution to understand the exciton states. This model gives a natural account for the PL blue shift with the increase of the excitation power. This study thus provides an alternative way to understand the underlying physics of the exciton dynamics in coupled potential wells.

C.S. Liu; T.F. Xu; Y.H. Liu; X.L. Jing

2014-01-01T23:59:59.000Z

134

The Invariant Set Postulate: A New Geometric Framework for the Foundations of Quantum Theory and the Role Played by Gravity  

E-Print Network (OSTI)

A new law of physics is proposed, defined on the cosmological scale but with significant implications for the microscale. Motivated by nonlinear dynamical systems theory and black-hole thermodynamics, the Invariant Set Postulate proposes that cosmological states of physical reality belong to a non-computable fractal state-space geometry I, invariant under the action of some subordinate deterministic causal dynamics. An exploratory analysis is made of a possible causal realistic framework for quantum physics, based on key properties of I. For example, sparseness is used to relate generic counterfactual states to points not lying on I, thus providing a geometric basis for the essential contextuality of quantum physics and the role of the abstract Hilbert Space in quantum theory. Also, self-similarity, described in a symbolic setting, provides a possible "realistic" perspective on the essential role of complex numbers and quaternions in quantum theory. A new interpretation is given to the standard "mysteries" of quantum theory: superposition, measurement, nonlocality, emergence of classicality and so on. It is proposed that heterogeneities in the fractal geometry of I are manifestations of the phenomenon of gravity. Since quantum theory is inherently blind to the existence of such state-space geometries, the analysis here suggests that attempts to formulate unified theories of physics within a conventional quantum-theoretic framework are misguided, and that a successful quantum theory of gravity should unify the causal non-Euclidean geometry of space time with the atemporal fractal geometry of state space.

T. N. Palmer

2009-06-30T23:59:59.000Z

135

Relativistic Quantum Field Theory with a Physical State Vector  

E-Print Network (OSTI)

Evolution of a physical quantum state vector is described as governed by two distinct physical laws: Continuous, unitary time evolution and a relativistically covariant reduction process. In previous literature, it was concluded that a relativistically satisfactory version of the collapse postulate is in contradiction with physical measurements of a non-local state history. Here it is shown that such measurements are excluded when reduction is formulated as a physical process and the measurement devices are included as part of the state vector.

Bernd A. Berg

1998-07-17T23:59:59.000Z

136

A lattice bosonic model as a quantum theory of gravity Zheng-Cheng Gu  

E-Print Network (OSTI)

model on a lattice is constructed whose low energy excitations are gravitons described by linearized a quantum theory of gravity. Seven wonders of our universe: Our world has many mysteries and wonders) Identical particles. (2) Gauge interactions.1­3 (3) Fermi statistics.4,5 (4) Tiny masses of fermions ( 10

Wen, Xiao-Gang

137

Coupled-Channels Quantum Theory of Electronic Flux Density in Electronically Adiabatic Processes: Fundamentals  

Science Journals Connector (OSTI)

Coupled-Channels Quantum Theory of Electronic Flux Density in Electronically Adiabatic Processes: Fundamentals ... Ones understanding of the mechanism of this fundamental reaction, as well as those of other arguably more important electronically adiabatic processes, should be significantly advanced by a knowledge of the electronic flux density (je). ...

D. J. Diestler

2011-11-21T23:59:59.000Z

138

Split-quaternionic Hopf map, quantum Hall effect, and twistor theory  

SciTech Connect

Introducing a noncompact version of the Hopf map, we demonstrate remarkable close relations between quantum Hall effect and twistor theory. We first construct quantum Hall effect on a hyperboloid based on the noncompact 2nd Hopf map of split-quaternions. We analyze a hyperbolic one-particle mechanics, and explore many-body problem, where a many-body ground state wave function and membrane-like excitations are derived explicitly. In the lowest Landau level, the symmetry is enhanced from SO(3,2) to the SU(2,2) conformal symmetry. We point out that the quantum Hall effect naturally realizes the philosophy of twistor theory. In particular, emergence mechanism of fuzzy space-time is discussed somehow in detail.

Hasebe, Kazuki [Department of General Education, Kagawa National College of Technology, Takuma-cho, Mitoyo-city, Kagawa 769-1192 (Japan)

2010-02-15T23:59:59.000Z

139

Quantum Theory of Chiral Interactions in Cholesteric Liquid Crystals  

E-Print Network (OSTI)

We study the effective chiral interaction between molecules arising from quantum dispersion interactions within a model in which a) the dominant excited states of a molecule form a band whose width is small compared to the average excitation energy and b) biaxial orientational correlation between adjacent molecules can be neglected. Previous treatments of quantum chiral interactions were based on a multipole expansion of the intermolecular interaction. However, because real liquid crystals are composed of elongated molecules, we utilize an expansion in terms of only coordinates transverse to the long molecular axes. We identify two distinct physical limits depending on whether one or both of the interacting molecules are excited in the virtual state. When both molecules are excited, our results are similar to those found previously by van der Meer et al. Previously unidentified terms in which only one molecule is excited involve the interactions of local dipole moments, which exist even when the global dipole moment of the molecule vanishes. We present analytic and numerical results for helical molecules. Our results do not indicate whether the dominant chiral interaction in cholesterics results from quantum or from steric interactions.

A. S. Issaenko; A. B. Harris; T. C. Lubensky

1998-10-15T23:59:59.000Z

140

Density Functional Theory applied to the solid state...  

E-Print Network (OSTI)

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

Adler, Joan

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


141

'Beyond quantum theory: a realist psycho-biological interpretation of reality' revisited  

E-Print Network (OSTI)

It is hypothesised, following Conrad et al. (1988) (http://www.tcm.phy.cam.ac.uk/~bdj10/papers/urbino.html) that quantum physics is not the ultimate theory of nature, but merely a theoretical account of the phenomena manifested in nature under particular conditions. These phenomena parallel cognitive phenomena in biosystems in a number of ways and are assumed to arise from related mechanisms. Quantum and biological accounts are complementary in the sense of Bohr and quantum accounts may be incomplete. In particular, following ideas of Stapp, 'the observer' is a system that, while lying outside the descriptive capacities of quantum mechanics, creates observable phenomena such as wave function collapse through its probing activities. Better understanding of such processes may pave the way to new science.

Brian D. Josephson

2001-05-08T23:59:59.000Z

142

Relationship of Quantum Entanglement to Density Functional Theory  

E-Print Network (OSTI)

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

A. K. Rajagopal; R. W. Rendell

2005-12-13T23:59:59.000Z

143

Toward theory of quantum Hall effect in graphene  

E-Print Network (OSTI)

We analyze a gap equation for the propagator of Dirac quasiparticles and conclude that in graphene in a magnetic field, the order parameters connected with the quantum Hall ferromagnetism dynamics and those connected with the magnetic catalysis dynamics necessarily coexist (the latter have the form of Dirac masses and correspond to excitonic condensates). This feature of graphene could lead to important consequences, in particular, for the existence of gapless edge states. Solutions of the gap equation corresponding to recently experimentally discovered novel plateaus in graphene in strong magnetic fields are described.

E. V. Gorbar; V. P. Gusynin; V. A. Miransky

2007-10-18T23:59:59.000Z

144

Microscopic Quantum Interference in the Theory of Superconductivity  

Science Journals Connector (OSTI)

...INTERPRETATION OF RECENT RESULTS ON HE-3 BELOW 3 MK - NEW LIQUID-PHASE, PHYSICAL REVIEW LETTERS...MAGNETIC PHENOMENA IN LIQUID HE-3 BELOW 3 MK, PHYSICAL REVIEW LETTERS 29 : 920 ( 1972...left). Comparison of 3.0 observed ultra-sonic attenuation with the ideal theory...

Leon N Cooper

1973-09-07T23:59:59.000Z

145

Quantum Theory of ?erenkov Radiation, Spectral Cutoff and Resonances  

E-Print Network (OSTI)

We show that the well-established \\v{C}erenkov Effect contains new phenomena arising directly from the quantum nature of the charged particles. These include large deviations from the classically-expected radiation intensity and angle. Most importantly, we find that the traditional Cerenkov angle splits, confining the emitted radiation into two distinctive cones into which two photonic shock waves are emitted. Interestingly, one of the two shockwaves can move on a backward cone, which is otherwise considered impossible for \\v{C}erenkov Radiaiton in ordinary materials. Moreover, for specific values of the particle momentum, we predict an upper frequency cutoff in the photon emission. Surprisingly, for this extremum frequency we find a diverging rate of photon emission, implying this is a new resonant light-matter interaction. Some of these new effects cannot be found without the full quantum derivation. Importantly, our findings are observable for electron beams with realistic parameters, offering new applications including coherent x-ray sources and open a new realm for \\v{C}erenkov detectors.

Ido Kaminer; Maor Mutzafi; Gal Harari; Hanan Herzig Sheinfux; Amir Levy; Scott Skirlo; Jonathan Nemirovsky; John D. Joannopoulos; Mordechai Segev; Marin Solja?i?

2014-11-01T23:59:59.000Z

146

A novel Artificial Neural Network training method combined with Quantum Computational Multi-Agent System theory  

Science Journals Connector (OSTI)

Artificial Neural Networks (ANNs) are powerful tools that can be used to model and investigate various complex and non-linear phenomena. In this study, we construct a new ANN, which is based on Multi-Agent System (MAS) theory and quantum computing algorithm. All nodes in this new ANN are presented as Quantum Computational (QC) agents, and these agents have learning ability. A novel ANN training method was proposed via implementing QCMAS reinforcement learning. This new ANN has powerful parallel-work ability and its training time is shorter than classic algorithm. Experiment results show that this method is effective.

Xiangping Meng; Jianzhong Wang; Yuzhen Pi; Quande Yuan

2009-01-01T23:59:59.000Z

147

The affine gauge theory in the quantum phase space CP(N-1)  

E-Print Network (OSTI)

In the present article I propose a non-linear relativistic 4-d field model originated by the internal dynamics in CP(N-1). There is no initially distinction between `particle' and `field', and the space-time manifold is derivable. The main idea is to base the theory on the relative amplitudes solely. Quantum measurements will be described in terms of the parallel transport of the local dynamical variables and a specific gauge reduction of the full state vector to the Qubit coherent state. I will discuss here field equations of quantum particle arising in the dynamical space-time.

Peter Leifer

2005-03-19T23:59:59.000Z

148

A quantum-dynamical theory for nonlinear optical interactions in graphene  

E-Print Network (OSTI)

We use a quantum-dynamical model to investigate the optical response of graphene under low excitation power. Ultrafast carrier relaxation processes, which play an important role for understanding the optical response of graphene, are included phenomenologically into the model. We obtain analytical solutions for the linear and third-order nonlinear optical response of graphene, and four-wave mixing in particular. This theory shows agreement with recently reported experimental data on linear complex optical conductivity and four-wave mixing, providing evidence for ultrafast quantum-dephasing times of approximately 1 fs.

Zheshen Zhang; Paul L. Voss

2011-06-23T23:59:59.000Z

149

Quantum theory of operation for rectenna solar cells  

Science Journals Connector (OSTI)

Optical rectennas, sub-micrometre antenna-coupled diodes, can directly rectify solar and thermal electromagnetic radiation, and have been proposed as an alternative to conventional semiconductor photovoltaics. We develop a comprehensive description of the operating principle of rectenna solar cells. In prior work classical concepts from microwave rectenna theory have been applied to the analysis of photovoltaic power generation using these ultra-high frequency rectifiers. Because of their high photon energy the interaction of petahertz frequency waves with fast-responding diodes requires a semiclassical analysis. We use the theory of photon-assisted transport to derive the currentvoltage [I(V)] characteristics of metal/insulator/metal tunnel diodes under illumination. We show how power is generated in the second quadrant of the I(V) characteristic, derive solar cell parameters, and analyse the key variables that influence the performance under monochromatic radiation and to a first order approximation. The efficiency improves with reduced dark current under reverse bias and increasing incident electromagnetic power.

Sachit Grover; Saumil Joshi; Garret Moddel

2013-01-01T23:59:59.000Z

150

Theory of coherent dynamic nuclear polarization in quantum dots  

Science Journals Connector (OSTI)

We consider the production of dynamic nuclear spin polarization (DNP) in a two-electron double quantum dot, in which the electronic levels are repeatedly swept through a singlet-triplet avoided crossing. Our analysis helps to elucidate the intriguing interplay between electron-nuclear hyperfine coupling, electronic spin-orbit coupling, and electron and nuclear Larmor precession in an externally applied magnetic field in guiding the production of DNP. In particular, we specifically address the roles of multiple nuclear spin species. By treating the nuclear spin dynamics semiclassically, we identify two contributions to the DNP production rate, a geometric contribution and a dynamic contribution, which depend in very different ways on control parameters such as the sweep rate and holding time near the level crossing. We find that the dynamical contribution dominates the DNP when the system is held near the singlet-triplet avoided crossing for a time on the order of the nuclear Larmor period. Detailed numerical calculations provide a physical picture for understanding the oscillations observed by Foletti et al. in arXiv:0801.3613.

Izhar Neder; Mark S. Rudner; Bertrand I. Halperin

2014-02-04T23:59:59.000Z

151

4d index to 3d index and 2d topological quantum field theory  

Science Journals Connector (OSTI)

We compute the 4d superconformal index for N=1, 2 gauge theories on S1L(p,1), where L(p,1) is a lens space. We find that the 4d N=1, 2 index on S1L(p,1) reduces to a 3d N=2, 4 index on S1S2 in the large p limit, and to a 3d partition function on a squashed L(p,1) when the size of the temporal S1 shrinks to zero. As an application of our index, we study 4d N=2 superconformal field theories arising from the 6d N=(2,0) A1 theory on a punctured Riemann surface ?, and conjecture the existence of a 2d topological quantum field theory on ? whose correlation function coincides with the 4d N=2 index on S1L(p,1).

Francesco Benini; Tatsuma Nishioka; Masahito Yamazaki

2012-09-10T23:59:59.000Z

152

Near quantitative agreement of model free DFT- MD predictions...  

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Near quantitative agreement of model free DFT- MD predictions with XAFS observations of the hydration structure of highly Near quantitative agreement of model free DFT- MD...

153

Dynamical behavior of spatially inhomogeneous relativistic $? ?^4$ quantum field theory in the Hartree approximation  

E-Print Network (OSTI)

We study the dynamics of a spatially inhomogeneous quantum $\\lambda \\phi^4$ field theory in 1+1 dimensions in the Hartree approximation. In particular, we investigate the long-time behavior of this approximation in a variety of controlled situations, both at zero and finite temperature. The observed behavior is much richer than that in the spatially homogeneous case. Nevertheless, we show that the fields fail to thermalize in a canonical sense, as expected from analogous results in closely related (mean field) transport theory. We argue that this dynamical approximation is best suited as a means to study the short-time decay of spatially inhomogeneous fields and in the dynamics of coherent quasi-classical inhomogeneous configurations (e.g. solitons) in a background of dynamical self-consistent quantum fluctuations.

Luis M. A. Bettencourt; Karen Pao; J. G. Sanderson

2001-04-21T23:59:59.000Z

154

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

SciTech Connect

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

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

2014-04-28T23:59:59.000Z

155

Particle detectors in curved spacetime quantum field theory  

E-Print Network (OSTI)

Unruh-DeWitt particle detector models are studied in a variety of time-dependent and time-independent settings. We work within the framework of first-order perturbation theory and couple the detector to a massless scalar field. The necessity of switching on (off) the detector smoothly is emphasised throughout, and the transition rate is found by taking the sharp-switching limit of the regulator-free and finite response function. The detector is analysed on a variety of spacetimes: $d$-dimensional Minkowski, the Ba\\~nados-Teitelboim-Zanelli (BTZ) black hole, the two-dimensional Minkowski half-plane, two-dimensional Minkowski with a receding mirror, and the two- and four-dimensional Schwarzschild black holes. In $d$-dimensional Minkowski spacetime, the transition rate is found to be finite up to dimension five. In dimension six, the transition rate diverges unless the detector is on a trajectory of constant proper acceleration, and the implications of this divergence to the global embedding spacetime (GEMS) met...

Hodgkinson, Lee

2013-01-01T23:59:59.000Z

156

Particle detectors in curved spacetime quantum field theory  

E-Print Network (OSTI)

Unruh-DeWitt particle detector models are studied in a variety of time-dependent and time-independent settings. We work within the framework of first-order perturbation theory and couple the detector to a massless scalar field. The necessity of switching on (off) the detector smoothly is emphasised throughout, and the transition rate is found by taking the sharp-switching limit of the regulator-free and finite response function. The detector is analysed on a variety of spacetimes: $d$-dimensional Minkowski, the Ba\\~nados-Teitelboim-Zanelli (BTZ) black hole, the two-dimensional Minkowski half-plane, two-dimensional Minkowski with a receding mirror, and the two- and four-dimensional Schwarzschild black holes. In $d$-dimensional Minkowski spacetime, the transition rate is found to be finite up to dimension five. In dimension six, the transition rate diverges unless the detector is on a trajectory of constant proper acceleration, and the implications of this divergence to the global embedding spacetime (GEMS) methods are studied. In three-dimensional curved spacetime, the transition rate for the scalar field in an arbitrary Hadamard state is found to be finite and regulator-free. Then on the Ba\\~nados-Teitelboim-Zanelli (BTZ) black hole spacetime, we analyse the detector coupled to the field in the Hartle-Hawking vacua, under both transparent and reflective boundary conditions at infinity. Results are presented for the co-rotating detector, which responds thermally, and for the radially-infalling detector. In four-dimensional Schwarzschild spacetime, we proceed numerically, and the Hartle-Hawking, Boulware and Unruh vacua rates are compared. Results are presented for the case of the static detectors, which respond thermally, and also for the case of co-rotating detectors.

Lee Hodgkinson

2013-09-27T23:59:59.000Z

157

New Regulators for Quantum Field Theories with Compactified Extra Dimensions. II: Ultraviolet Finiteness and Effective Field Theory Implementation  

E-Print Network (OSTI)

In a previous companion paper [arXiv:0712.3532], we proposed two new regulators for quantum field theories in spacetimes with compactified extra dimensions. Unlike most other regulators which have been used in the extra-dimension literature, these regulators are specifically designed to respect the original higher-dimensional Lorentz and gauge symmetries that exist prior to compactification, and not merely the four-dimensional symmetries which remain afterward. In this paper, we use these regulators in order to develop a method for extracting ultraviolet-finite results from one-loop calculations. This method also allows us to derive Wilsonian effective field theories for Kaluza-Klein modes at different energy scales. Our method operates by ensuring that divergent corrections to parameters describing the physics of the excited Kaluza-Klein modes are absorbed into the corresponding parameters for zero modes, thereby eliminating the need to introduce independent counterterms for parameters characterizing different Kaluza-Klein modes. Our effective field theories can therefore simplify calculations involving Kaluza-Klein modes, and be compared directly to potential experimental results emerging from collider data.

Sky Bauman; Keith R. Dienes

2008-01-27T23:59:59.000Z

158

A Self-Consistent Formulation of Quantum Field Theory on $S_{4}$  

E-Print Network (OSTI)

Recent developments in quantum gravity suggest that wormholes may influence the observed values of the constants of nature. The Euclidean formulation of quantum gravity predicts that wormholes induce a probability distribution in the space of possible fundamental constants. This distribution may computed by evaluating the functional integral about the stationary points of the action. In particular, the effective action on a large spherical space may lead to the vanishing of the cosmological constant and possibly determine the values of other constants of nature. The ability to perform calculations involving interacting quantum fields, particularly non-Abelian models, on a four-sphere is vital if one is to investigate this possibility. In this paper we present a self-consistent formulation of field theory on a four-sphere using the angular momentum space representation of $SO(5)$. We give a review of field theory on a sphere and then show how a matrix element prescription in angular momentum space overcomes previous limitations in calculational techniques. The standard one-loop graphs of QED are given as examples.

B. A. Harris; G. C. Joshi

1992-12-02T23:59:59.000Z

159

Adsorption of silver dimer on graphene - A DFT study  

SciTech Connect

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.

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

160

Negative energy densities in integrable quantum field theories at one-particle level  

E-Print Network (OSTI)

We study the phenomenon of negative energy densities in quantum field theories with self-interaction. Specifically, we consider a class of integrable models (including the sinh-Gordon model) in which we investigate the expectation value of the energy density in one-particle states. In this situation, we classify the possible form of the stress-energy tensor from first principles. We show that one-particle states with negative energy density generically exist in non-free situations, and we establish lower bounds for the energy density (quantum energy inequalities). Demanding that these inequalities hold reduces the ambiguity in the stress-energy tensor, in some situations fixing it uniquely. Numerical results for the lowest spectral value of the energy density allow us to demonstrate how negative energy densities depend on the coupling constant and on other model parameters.

Bostelmann, Henning

2015-01-01T23:59:59.000Z

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


161

6-dimensional Kaluza-Klein Theory for Basic Quantum Particles and Electron-Photon Interaction  

E-Print Network (OSTI)

By extending original Kaluza-Klein theory to 6-dimension, the basic quantum field equations for 0-spin particle, 1-spin particle and 1/2 spin particle with mass >0 are directly derived from 6-dimensional Einstein equations. It shows that the current quantum field equations of basic particles become pure geometry properties under 6-dimension time-space. The field equations of electron and photon can be unified in one 6-dimensional extended Maxwell equation. The equations containing interactions between electron and photon will be derived from Einstein equation under 6-dimension time-space. It shows that the interactions in QED can be considered as the effect of local geometry curvature changing instead of exchange virtual photons.

Xiaodong Chen

2005-01-26T23:59:59.000Z

162

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

E-Print Network (OSTI)

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

Norbert Schuch; Frank Verstraete

2007-12-04T23:59:59.000Z

163

Quasi-Topological Quantum Field Theories and $Z_2$ Lattice Gauge Theories  

E-Print Network (OSTI)

We consider a two parameter family of $Z_2$ gauge theories on a lattice discretization $T(M)$ of a 3-manifold $M$ and its relation to topological field theories. Familiar models such as the spin-gauge model are curves on a parameter space $\\Gamma$. We show that there is a region $\\Gamma_0$ of $\\Gamma$ where the partition function and the expectation value $$ of the Wilson loop for a curve $\\gamma$ can be exactly computed. Depending on the point of $\\Gamma_0$, the model behaves as topological or quasi-topological. The partition function is, up to a scaling factor, a topological number of $M$. The Wilson loop on the other hand, does not depend on the topology of $\\gamma$. However, for a subset of $\\Gamma_0$, $$ depends on the size of $\\gamma$ and follows a discrete version of an area law. At the zero temperature limit, the spin-gauge model approaches the topological and the quasi-topological regions depending on the sign of the coupling constant.

Miguel J. B. Ferreira; Victor A. Pereira; P. Teotonio-Sobrinho

2012-06-11T23:59:59.000Z

164

Quantum Tetrahedra  

E-Print Network (OSTI)

We discuss in details the role of Wigner 6j symbol as the basic building block unifying such different fields as state sum models for quantum geometry, topological quantum field theory, statistical lattice models and quantum computing. The apparent twofold nature of the 6j symbol displayed in quantum field theory and quantum computing -a quantum tetrahedron and a computational gate- is shown to merge together in a unified quantum-computational SU(2)-state sum framework.

Mauro Carfora; Annalisa Marzuoli; Mario Rasetti

2010-01-25T23:59:59.000Z

165

The harmonic oscillator with dissipation within the theory of open quantum systems  

E-Print Network (OSTI)

Time evolution of the expectation values of various dynamical operators of the harmonic oscillator with dissipation is analitically obtained within the framework of the Lindblad theory for open quantum systems. We deduce the density matrix of the damped harmonic oscillator from the solution of the Fokker-Planck equation for the coherent state representation, obtained from the master equation for the density operator. The Fokker-Planck equation for the Wigner distribution function, subject to either the Gaussian type or the $\\delta$-function type of initial conditions, is also solved by using the Wang-Uhlenbeck method. The obtained Wigner functions are two-dimensional Gaussians with different widths.

A. Isar

2005-08-18T23:59:59.000Z

166

Modeling of electroabsorption in semiconductor quantum structures within the eight-band k?p theory  

Science Journals Connector (OSTI)

We have incorporated electric fields into the eight-band k?p theory, which we have applied to heterostructures, in conjunction with the envelope-function approximation. We use the method of Baraff and Gershoni to implement the electric-field effects in a computer program that calculates the optical properties of direct-band-gap heterostructures in one, two, and three dimensions. Using this method, we calculate the interband and intersubband electroabsorption of multiple quantum wells as well as the interband electroabsorption in superlattices. We illustrate the evolution of the Stark localization of the electron wave function under the application of an external electric field in superlattices. Comparison with experimental data, available in the literature, exhibits very good agreement between theory and experiment, with respect to the spectral shape, the absolute magnitude, and the electric-field dependence of the absorption.

Mats-Erik Pistol and David Gershoni

1994-10-15T23:59:59.000Z

167

Modeling of strained quantum wires using eight-band k?p theory  

Science Journals Connector (OSTI)

We have calculated numerically the one-dimensional band structure and densities of states of a V-shaped In0.2Ga0.8As/AlxGa1-xAs single quantum wire using eight-band k?p theory. A finite-difference scheme is used for the calculations. The model includes the realistic orientation, shape, material composition, strain distribution, and piezoelectric charging of the wire. We find a dominant impact of the piezoelectric potential on the band structure and a marked spin splitting of the valence bands. Also, the conduction band is strongly nonparabolic. We propose an efficient procedure to calculate interior eigenvectors from Hamiltonians including conduction-bandvalence-band interactions. This algorithm is 2090 times faster than the best prevailing method and also applies to other Hamiltonians for the modeling of nanostructures, including those occurring in tight-binding or pseudopotential theory.

O. Stier and D. Bimberg

1997-03-15T23:59:59.000Z

168

Quantum theory of large amplitude collective motion and the Born-Oppenheimer method  

E-Print Network (OSTI)

We study the quantum foundations of a theory of large amplitude collective motion for a Hamiltonian expressed in terms of canonical variables. In previous work the separation into slow and fast (collective and non-collective) variables was carried out without the explicit intervention of the Born Oppenheimer approach. The addition of the Born Oppenheimer assumption not only provides support for the results found previously in leading approximation, but also facilitates an extension of the theory to include an approximate description of the fast variables and their interaction with the slow ones. Among other corrections, one encounters the Berry vector and scalar potential. The formalism is illustrated with the aid of some simple examples, where the potentials in question are actually evaluated and where the accuracy of the Born Oppenheimer approximation is tested. Variational formulations of both Hamiltonian and Lagrangian type are described for the equations of motion for the slow variables.

Abraham Klein; Niels R. Walet

1993-03-20T23:59:59.000Z

169

Ambiguities and Subtleties in Fermion Mass Terms in Practical Quantum Field Theory  

E-Print Network (OSTI)

This is a review on structure of the fermion mass terms in quantum field theory, under the perspective of its practical applications in the real physics of Nature -- specifically, we discuss fermion mass structure in the Standard Model of high energy physics, which successfully describes fundamental physics up to the TeV scale. The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the textbooks. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least so long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). Especially, for the case of neutrinos, the use of the Dirac or Majorana terminology may be mostly a matter of choice. The common usage of such terminology is rather based on the broken $SU(2)$ charges of the related Weyl spinors hence conventional and may not be unambiguously extended to cover more complicate models.

Yifan Cheng; Otto C. W. Kong

2014-08-05T23:59:59.000Z

170

The Measurement Process in Local Quantum Theory and the EPR Paradox  

E-Print Network (OSTI)

We describe in a qualitative way a possible picture of the Measurement Process in Quantum Mechanics, which takes into account: 1. the finite and non zero time duration T of the interaction between the observed system and the microscopic part of the measurement apparatus; 2. the finite space size R of that apparatus; 3. the fact that the macroscopic part of the measurement apparatus, having the role of amplifying the effect of that interaction to a macroscopic scale, is composed by a very large but finite number N of particles. The conventional picture of the measurement, as an instantaneous action turning a pure state into a mixture, arises only in the limit in which N and R tend to infinity, and T tends to 0. We sketch here a proposed scheme, which still ought to be made mathematically precise in order to analyse its implications and to test it in specific models, where we argue that in Quantum Field Theory this picture should apply to the unique time evolution expressing the dynamics of a given theory, and should comply with the Principle of Locality. We comment on the Einstein Podolski Rosen thought experiment (partly modifying the discussion on this point in an earlier version of this note), reformulated here only in terms of local observables (rather than global ones, as one particle or polarisation observables). The local picture of the measurement process helps to make it clear that there is no conflict with the Principle of Locality.

Sergio Doplicher

2009-08-04T23:59:59.000Z

171

Accurate nonadiabatic quantum dynamics on the cheap: making the most of mean field theory with master equations  

E-Print Network (OSTI)

In this article we show how Ehrenfest mean field theory can be made both a more accurate and efficient method to treat nonadiabatic quantum dynamics by combining it with the generalized quantum master equation framework. The resulting mean field generalized quantum master equation (MF-GQME) approach is a non-perturbative and non-Markovian theory that can be applied to open quantum systems without requiring a particular form of the interactions. By studying relaxation dynamics in a wide range of dynamical regimes, typical of charge and energy transfer, we show that MF-GQME provides a much higher accuracy than a direct application of mean field theory. In addition, these increases in accuracy are accompanied by computational speed-ups of between one and two orders of magnitude that become larger as the system becomes more nonadiabatic. This combination of quantum-classical theory and master equation techniques thus makes it possible to obtain the accuracy of much more computationally expensive approaches at a c...

Kelly, Aaron; Markland, Thomas E

2015-01-01T23:59:59.000Z

172

Screened Hybrid and DFT + U Studies of the Structural, Electronic...  

NLE Websites -- All DOE Office Websites (Extended Search)

Screened Hybrid and DFT + U Studies of the Structural, Electronic, and Optical Properties of U3O8. Screened Hybrid and DFT + U Studies of the Structural, Electronic, and Optical...

173

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

E-Print Network (OSTI)

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

Cheng, Chiao-Lun

2008-01-01T23:59:59.000Z

174

Ab Initio Geometry and Bright Excitation of Carotenoids: Quantum Monte Carlo and Many Body Green's Function Theory Calculations  

E-Print Network (OSTI)

Ab Initio Geometry and Bright Excitation of Carotenoids: Quantum Monte Carlo and Many Body Green state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy and coupling with Qy of the chlorophyll.8-13 Measurements in several solvents have been reported

Guidoni, Leonardo

175

Quantum dissipative dynamics of adsorbates near metal surfaces: A surrogate Hamiltonian theory applied to hydrogen on nickel  

E-Print Network (OSTI)

Quantum dissipative dynamics of adsorbates near metal surfaces: A surrogate Hamiltonian theory; accepted 18 February 1997 Dissipative dynamics of an adsorbate near a metal surface is formulated of molecules adsorbed on metal surfaces are complicated due to the simultaneous encounter with dis- sipative

Baer, Roi

176

Atomic and Molecular Quantum Theory Course Number: C561 23 The Born-Oppenheimer approximation, the Many Electron  

E-Print Network (OSTI)

Atomic and Molecular Quantum Theory Course Number: C561 23 The Born-Oppenheimer approximation are required. One powerful approximation is called the Born-Oppenheimer approximation. (It does have some limitations and we will discuss these as well.) The Born-Oppenheimer approximation assumes that the nuclei

Iyengar, Srinivasan S.

177

Asymptotic states and renormalization in Lorentz-violating quantum field theory  

E-Print Network (OSTI)

Asymptotic single-particle states in quantum field theories with small departures from Lorentz symmetry are investigated perturbatively with focus on potential phenomenological ramifications. To this end, one-loop radiative corrections for a sample Lorentz-violating Lagrangian contained in the Standard-Model Extension (SME) are studied at linear order in Lorentz breakdown. It is found that the spinor kinetic operator, and thus the free-particle physics, is modified by Lorentz-violating operators absent from the original Lagrangian. As a consequence of this result, both the standard renormalization procedure as well as the Lehmann-Symanzik-Zimmermann reduction formalism need to be adapted. The necessary adaptations are worked out explicitly at first order in Lorentz-breaking coefficients.

Mauro Cambiaso; Ralf Lehnert; Robertus Potting

2014-01-28T23:59:59.000Z

178

hal-00263678,version2-2Apr2008 On group theory for quantum gates  

E-Print Network (OSTI)

of the three pillars: quantum physics, mathematics and computer science. If large-scale quantum computers can of the stabilizer group in terms of maximal normal subgroups [16], sustain the explanation of quantum (de

Paris-Sud XI, Université de

179

Engineering of Quantum Hall Effect from Type IIA String Theory on The K3 Surface  

E-Print Network (OSTI)

Using D-brane configurations on the K3 surface, we give six dimensional type IIA stringy realizations of the Quantum Hall Effect (QHE) in 1+2 dimensions. Based on the vertical and horizontal lines of the K3 Hodge diamond, we engineer two different stringy realizations. The vertical line presents a realization in terms of D2 and D6-branes wrapping the K3 surface. The horizontal one is associated with hierarchical stringy descriptions obtained from a quiver gauge theory living on a stack of D4-branes wrapping intersecting 2-spheres embedded in the K3 surface with deformed singularities. These geometries are classified by three kinds of the Kac-Moody algebras: ordinary, i.e finite dimensional, affine and indefinite. We find that no stringy QHE in 1+2 dimensions can occur in the quiver gauge theory living on intersecting 2-spheres arranged as affine Dynkin diagrams. Stringy realizations of QHE can be done only for the finite and indefinite geometries. In particular, the finite Lie algebras give models with fractional filling fractions, while the indefinite ones classify models with negative filling fractions which can be associated with the physics of holes in the graphene.

Adil Belhaj; Antonio Segui

2010-07-02T23:59:59.000Z

180

Bohr - Planck quantum theory, (Tesla) magnetic monopoles and fine structure constant  

E-Print Network (OSTI)

In this work we apply Bohr-Planck (Old quantum atomic and radiation) theory, i.e. and quasi-classical methods for analysis of the magnetic monopoles and other problems. We reproduce exactly some basic elements of the Dirac magnetic monopoles theory, especially Dirac electric/magnetic charge quantization condition. Also, we suggest a new, effective, simply called Tesla model (for analogy with positions of the solenoids by Tesla inductive motor) of the magnetic monopole instead of usual effective Dirac model (half-infinite, very tinny solenoid) of the magnetic monopole. In our, i.e. Tesla model we use three equivalent tiny solenoids connected in series with a voltage source. One end of any solenoid is placed at the circumference of a circle and solenoids are directed radial toward circle center. Length of any solenoid is a bit smaller than finite circle radius so that other end of any solenoid is very close to the circle center. Angles between neighboring solenoids equal $120^{\\circ}$. All this implies that, practically, there is no magnetic field, or, magnetic pole, e.g. $S$, in the circle center, and that whole system holds only other, $N$ magnetic pole, at the ends of the solenoids at circle circumference. Finally, we reproduce relatively satisfactory value of the fine structure constant using Planck, i.e. Bose-Einstein statistics and Wien displacement law.

Vladan Pankovic; Darko V. Kapor; Stevica Djurovic; Miodrag Krmar

2014-10-17T23:59:59.000Z

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


181

New Regulators for Quantum Field Theories with Compactified Extra Dimensions. I: Fundamentals  

E-Print Network (OSTI)

In this paper, we propose two new regulators for quantum field theories in spacetimes with compactified extra dimensions. We refer to these regulators as the ``extended hard cutoff'' (EHC) and ``extended dimensional regularization'' (EDR). Although based on traditional four-dimensional regulators, the key new feature of these higher-dimensional regulators is that they are specifically designed to handle mixed spacetimes in which some dimensions are infinitely large and others are compactified. Moreover, unlike most other regulators which have been used in the extra-dimension literature, these regulators are designed to respect the original higher-dimensional Lorentz and gauge symmetries that exist prior to compactification, and not merely the four-dimensional symmetries which remain afterward. This distinction is particularly relevant for calculations of the physics of the excited Kaluza-Klein modes themselves, and not merely their radiative effects on zero modes. By respecting the full higher-dimensional symmetries, our regulators avoid the introduction of spurious terms which would not have been easy to disentangle from the physical effects of compactification. As part of our work, we also derive a number of ancillary results. For example, we demonstrate that in a gauge-invariant theory, analogues of the Ward-Takahashi identity hold not only for the usual zero-mode (four-dimensional) photons, but for all excited Kaluza-Klein photons as well.

Sky Bauman; Keith R. Dienes

2007-12-20T23:59:59.000Z

182

DFT investigation on the electronic structure of Faujasite  

SciTech Connect

We report here first-principle pseudopotential DFT calculations to investigate relevant aspects of the electronic structure of zeolites based FAU. Fundamental molecular issues of the band-gap and electronic population analysis were reviewed under GGA/RPBE level of theory, corroborated with a DZP basis set and Troullier-Martins norm conserving pseudo-potentials. The atom-projected density of states and the analysis of HOMO-LUMO frontier orbitals at Gamma point were performed. Their electronic transfers are discussed through the alignment and relative positions of orbitals in order to determine the way that the molecule interacts with adsorbed molecules and other practical applications. Mulliken population analysis was employed for describing atomic charge distribution in the chosen systems.

Popeneciu, Horea; Calborean, Adrian; Tudoran, Cristian; Buimaga-Iarinca, Luiza [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

183

Triplet absorption in carbon nanotubes: a TD-DFT study  

E-Print Network (OSTI)

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.

Sergei Tretiak

2007-02-13T23:59:59.000Z

184

Augmented Lagrangian Method for Constrained Nuclear Density Functional Theory  

E-Print Network (OSTI)

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

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

2010-07-21T23:59:59.000Z

185

ORBITAL-FREE KINETIC-ENERGY DENSITY FUNCTIONAL THEORY  

E-Print Network (OSTI)

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

Wang, Yan Alexander

186

Benchmark density functional theory calculations for nanoscale conductance  

E-Print Network (OSTI)

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

Thygesen, Kristian

187

Hypercomplex Algebras and their application to the mathematical formulation of Quantum Theory  

E-Print Network (OSTI)

Quantum theory (QT), namely in terms of Schr\\"odinger's 1926 wave functions in general requires complex numbers to be formulated. However, it soon turned out to even require some hypercomplex algebra. Incorporating Special Relativity leads to an equation (Dirac 1928) requiring pairwise anti-commuting coefficients, usually $4\\times 4$ matrices. A unitary ring of square matrices is an associative hypercomplex algebra by definition. Since only the algebraic properties and relations of the elements matter, we replace the matrices by biquaternions. In this paper, we first consider the basics of non-relativistic and relativistic QT. Then we introduce general hypercomplex algebras and also show how a relativistic quantum equation like Dirac's one can be formulated using biquaternions. Subsequently, some algebraic preconditions for operations within hypercomplex algebras and their subalgebras will be examined. For our purpose equations akin to Schr\\"odinger's should be able to be set up and solved. Functions of complementary variables should be Fourier transforms of each other. This should hold within a purely non-real subspace which must hence be a subalgebra. Furthermore, it is an ideal denoted by $\\mathcal{J}$. It must be isomorphic to $\\mathbb{C}$, hence containing an internal identity element. The bicomplex numbers will turn out to fulfil these preconditions, and therefore, the formalism of QT can be developed within its subalgebras. We also show that bicomplex numbers encourage the definition of several different kinds of conjugates. One of these treats the elements of $\\mathcal{J}$ like the usual conjugate treats complex numbers. This defines a quantity what we call a modulus which, in contrast to the complex absolute square, remains non-real (but may be called `pseudo-real'). However, we do not conduct an explicit physical interpretation here but we leave this to future examinations.

Torsten Hertig; Jens Philip Hhmann; Ralf Otte

2014-06-04T23:59:59.000Z

188

Quantum field theory in curved graphene spacetimes, Lobachevsky geometry, Weyl symmetry, Hawking effect, and all that  

E-Print Network (OSTI)

The solutions of many issues, of the ongoing efforts to make deformed graphene a tabletop quantum field theory in curved spacetimes, are presented. A detailed explanation of the special features of curved spacetimes, originating from embedding portions of the Lobachevsky plane into $\\mathbf{R}^3$, is given, and the special role of coordinates for the physical realizations in graphene, is explicitly shown, in general, and for various examples. The Rindler spacetime is reobtained, with new important differences with respect to earlier results. The de Sitter spacetime naturally emerges, for the first time, paving the way to future applications in cosmology. The role of the BTZ black hole is also briefly addressed. The singular boundary of the pseudospheres, "Hilbert horizon", is seen to be closely related to event horizon of the Rindler, de Sitter, and BTZ kind. This gives new, and stronger, arguments for the Hawking phenomenon to take place. An important geometric parameter, $c$, overlooked in earlier work, takes here its place for physical applications, and it is shown to be related to graphene's lattice spacing, $\\ell$. It is shown that all surfaces of constant negative curvature, ${\\cal K} = -r^{-2}$, are unified, in the limit $c/r \\to 0$, where they are locally applicable to the Beltrami pseudosphere. This, and $c = \\ell$, allow us a) to have a phenomenological control on the reaching of the horizon; b) to use spacetimes different than Rindler for the Hawking phenomenon; c) to approach the generic surface of the family. An improved expression for the thermal LDOS is obtained. A non-thermal term for the total LDOS is found. It takes into account: a) the peculiarities of the graphene-based Rindler spacetime; b) the finiteness of a laboratory surface; c) the optimal use of the Minkowski quantum vacuum, through the choice of this Minkowski-static boundary.

Alfredo Iorio; Gaetano Lambiase

2014-12-15T23:59:59.000Z

189

From Quantum Field Theory to Nano-Optics : Refractive Properties of Graphene in a Medium-Strong Magnetic field  

E-Print Network (OSTI)

1-loop quantum corrections are shown to induce large effects on the refraction index n inside a graphene strip in the presence of an external magnetic field B orthogonal to it. To this purpose, we use the tools of Quantum Field Theory to calculate the photon propagator at 1-loop inside graphene in position space, which leads to an effective vacuum polarization in a brane-like theory of photons interacting with massless electrons at locations confined inside the thin strip (its longitudinal spread is considered to be infinite). The effects factorize into quantum ones, controlled by the value of B and that of the electromagnetic coupling alpha, and a "transmittance function" U in which the geometry of the sample and the resulting confinement of electrons play the major roles. We consider photons inside the visible spectrum and magnetic fields in the range 1-20 Teslas. At B=0, quantum effects depend very weakly on alpha and n is essentially controlled by U; we recover, then, an opacity for visible light of the same order of magnitude pi * alpha_{vac} as measured experimentally.

Olivier Coquand; Bruno Machet

2014-07-08T23:59:59.000Z

190

Finite temperature quantum field theory on non compact domains and application to delta interactionsinteractions in three dimensions  

E-Print Network (OSTI)

We use relative zeta functions technique of W. Muller \\cite{Mul} to extend the classical decomposition of the zeta regularized partition function of a finite temperature quantum field theory on a ultrastatic space-time with compact spatial section to the case of non compact spatial section. As an application, we study the case of Schr\\"odinger operators with delta like potential, as described by Albeverio & alt. in \\cite{AGHH}.

Mauro Spreafico; Sergio Zerbini

2007-08-30T23:59:59.000Z

191

The Casimir effect from the point of view of algebraic quantum field theory  

E-Print Network (OSTI)

We consider a region of Minkowski spacetime bounded either by one or by two parallel, infinitely extended plates orthogonal to a spatial direction and a real Klein-Gordon field satisfying Dirichlet boundary conditions. We quantize these two systems within the algebraic approach to quantum field theory using the so-called functional formalism. As a first step we construct a suitable unital *-algebra of observables whose generating functionals are characterized by a labeling space which is at the same time optimal and separating. Subsequently we give a definition for these systems of Hadamard states and we investigate explicit examples. In the case of a single plate, it turns out that one can build algebraic states via a pull-back of those on the whole Minkowski spacetime, moreover inheriting from them the Hadamard property. When we consider instead two plates, algebraic states can be put in correspondence with those on flat spacetime via the so-called method of images, which we translate to the algebraic setting. For a massless scalar field we show that this procedure works perfectly for a large class of quasi-free states including the Poincar\\'e vacuum and KMS states. Eventually we use our results in both systems to introduce the notion of Wick polynomials, showing that a global extended algebra does not exist. Furthermore we construct explicitly the two-point function and the regularized energy density, showing, moreover, that the outcome is consistent with the standard results of the Casimir effect.

Claudio Dappiaggi; Gabriele Nosari; Nicola Pinamonti

2014-12-03T23:59:59.000Z

192

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

SciTech Connect

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

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

2014-03-28T23:59:59.000Z

193

Theory of terahertz/near-infrared optical mixing in quantum wells in strong magnetic fields Takeshi Inoshita, Junichiro Kono,* and Hiroyuki Sakaki  

E-Print Network (OSTI)

Theory of terahertz/near-infrared optical mixing in quantum wells in strong magnetic fields TakeshiAs quantum wells illuminated simultaneously by near-infrared and terahertz THz radiation in strong magnetic the sample is illuminated simul- taneously by THz frequency T) and near-infrared fre- quency N) radiation

Kono, Junichiro

194

Quantum theory, gravity, and the standard model of particle physics : using the hints of today to build the final theory of tomorrow  

E-Print Network (OSTI)

When a mountaineer is ascending one of the great peaks of the Himalayas she knows that an entirely new vista awaits her at the top, whose ramifications will be known only after she gets there. Her immediate goal though, is to tackle the obstacles on the way up, and reach the summit. In a similar vein, one of the immediate goals of contemporary theoretical physics is to build a quantum, unified description of general relativity and the standard model of particle physics. Once that peak has been reached, a new (yet unknown) vista will open up. In this essay I propose a novel approach towards this goal. One must address and resolve a fundamental unsolved problem in the presently known formulation of quantum theory : the unsatisfactory presence of an external classical time in the formulation. Solving this problem takes us to the very edge of theoretical physics as we know it today!

T. P. Singh

2010-01-19T23:59:59.000Z

195

Theory of ballistic transport through a 3D-1D-3D quantum system  

Science Journals Connector (OSTI)

Ballistic transport through a three-dimensionalone-dimensionalthree-dimensional quantum system has been studied theoretically. Based on an exact quantum-mechanical formulation, the quantization of the conductance in units of 2e2/h of this vertical analog to the split-gate defined quantum channel in a two-dimensional electron gas has been proved. By taking into account the mode degeneracy in the lateral confined quantum pillar, multiple conductance plateaus, i.e., the conductance changes in steps of multiples of 2e2/h, are shown to appear in the quantum system.

Hongqi Xu

1993-09-15T23:59:59.000Z

196

Session #1: Cutting Edge Methodologies--Beyond Current DFT  

Energy.gov (U.S. Department of Energy (DOE))

Benchmarking state-of-the-art approaches, accurate energy landscape. Identify problems with the current DFT-LDA and GGA approaches and possible pathways to overcome these problems.

197

A Proposed Alternative Low Energy Quantum Field Theory of Gravity Based on a Bose-Einstein Condensate Effect  

E-Print Network (OSTI)

An alternative quantum field theory for gravity is proposed for low energies based on an attractive effect between contaminants in a Bose-Einstein Condensate rather than on particle exchange. In the ``contaminant in condensate effect," contaminants cause a potential in an otherwise uniform condensate, forcing the condensate between two contaminants to a higher energy state. The energy of the system decreases as the contaminants come closer together, causing an attractive force between contaminants. It is proposed that mass-energy may have a similar effect on Einstein's space-time field, and gravity is quantized by the same method by which the contaminant in condensate effect is quantized. The resulting theory is finite and, if a physical condensate is assumed to underly the system, predictive. However, the proposed theory has several flaws at high energies and is thus limited to low energies. Falsifiable predictions are given for the case that the Higgs condensate is assumed to be the condensate underlying gravity.

Alexander Oshmyansky

2007-03-08T23:59:59.000Z

198

Perturbation Theory Based on Darboux Transformation on One-Dimensional Dirac Equation in Quantum Computation  

E-Print Network (OSTI)

We present the recent works \\cite{trisetyarso2011} on the application of Darboux transformation on one-dimensional Dirac equation related to the field of Quantum Information and Computation (QIC). The representation of physical system in one-dimensional equation and its transformation due to the Bagrov, Baldiotti, Gitman, and Shamshutdinova (BBGS)-Darboux transformation showing the possibility admitting the concept of relativity and the trade-off of concurrent condition of quantum and classical physics play into the area of QIC. The applications in cavity quantum electrodynamics and on the proposal of quantum transistor are presented.

Agung Trisetyarso

2014-11-23T23:59:59.000Z

199

Density Functional Theory for Superconductors  

E-Print Network (OSTI)

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

Gross, E.K.U.

200

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

E-Print Network (OSTI)

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

Armiento, Rickard

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201

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

E-Print Network (OSTI)

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

Ortiz, Michael

202

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

E-Print Network (OSTI)

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

Wang, Yan Alexander

203

Quantum Chromodynamics  

Science Journals Connector (OSTI)

The theory of the strong interaction of elementary particles, Quantum Chromodynamics (QCD), is a non-abelian gauge theory with SU(3) as gauge group. The degrees of freedom corresponding to this SU(3) are called c...

Prof. Dr. rer. nat. Manfred Bhm

2001-01-01T23:59:59.000Z

204

Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory  

SciTech Connect

We generalize unitarity bounds on operator dimensions in conformal field theory to field theories with spacetime dependent couplings. Below the energy scale of spacetime variation of the couplings, their evolution can strongly affect the physics, effectively shifting the infrared operator scaling and unitarity bounds determined from correlation functions in the theory. We analyze this explicitly for large-N double-trace flows, and connect these to UV complete field theories. One motivating class of examples comes from our previous work on FRW holography, where this effect explains the range of flavors allowed in the dual, time dependent, field theory.

Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC

2012-04-05T23:59:59.000Z

205

The Dirac equation in electronic structure calculations: Accurate evaluation of DFT predictions for actinides  

SciTech Connect

Brooks, Johansson, and Skriver, using the LMTO-ASA method and considerable insight, were able to explain many of the ground state properties of the actinides. In the many years since this work was done, electronic structure calculations of increasing sophistication have been applied to actinide elements and compounds, attempting to quantify the applicability of DFT to actinides and actinide compounds and to try to incorporate other methodologies (i.e. DMFT) into DFT calculations. Through these calculations, the limits of both available density functionals and ad hoc methodologies are starting to become clear. However, it has also become clear that approximations used to incorporate relativity are not adequate to provide rigorous tests of the underlying equations of DFT, not to mention ad hoc additions. In this talk, we describe the result of full-potential LMTO calculations for the elemental actinides, comparing results obtained with a full Dirac basis with those obtained from scalar-relativistic bases, with and without variational spin-orbit. This comparison shows that the scalar relativistic treatment of actinides does not have sufficient accuracy to provide a rigorous test of theory and that variational spin-orbit introduces uncontrolled errors in the results of electronic structure calculations on actinide elements.

Wills, John M [Los Alamos National Laboratory; Mattsson, Ann E [Sandia National Laboratories

2012-06-06T23:59:59.000Z

206

Engineering the unitary charge-conjugation operator of quantum field theory for particle-antiparticle using trapped ions and light fields in cavity QED  

E-Print Network (OSTI)

We present a method to engineer the unitary charge conjugation operator, as given by quantum field theory, in the highly controlled context of quantum optics, thus allowing one to simulate the creation of charged particles with well-defined momenta simultaneously with their respective antiparticles. Our method relies on trapped ions driven by a laser field and interacting with a single mode of a light field in a high Q cavity.

N. G. de Almeida

2014-01-22T23:59:59.000Z

207

Taming Density Functional Theory by Coarse-Graining  

E-Print Network (OSTI)

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

Paul E. Lammert

2010-08-10T23:59:59.000Z

208

Modeling of molecular gas adsorption isotherms on porous materials with hybrid PC-SAFTDFT  

Science Journals Connector (OSTI)

Abstract The developed hybrid PC-SAFTDFT model, a coupling of density functional theory (DFT) with perturbed-chain statistical associating fluid theory (PC-SAFT), was used to study the adsorption of pure- and mixed-fluids on nano-porous materials, and carbons and zeolites were chosen as examples of nano-porous materials in this work for model performance evaluation. In the PC-SAFTDFT model, the modified fundamental measure theory was used for the hard sphere contribution, the dispersion free energy functional was represented with a weighted density approximation, and the chain free energy functional from interfacial SAFT was used to account for the chain connectivity. The fluid was modeled as a chain molecule with molecular parameters taken from those in the bulk PC-SAFT. The external force field was used to describe the interaction between the solid surface of a nano-porous material and fluid. Application of this model was demonstrated on the gas adsorption on porous carbons and zeolites which were assumed to have slit- and cylinder-shaped pores with mean pore sizes, respectively. The parameters of the adsorption model were obtained by fitting to the pure-gas adsorption isotherms measured experimentally. With parameters of the model fitted to the pure-gas adsorption at one temperature, the model was used to predict the pure-gas adsorption at other temperatures as well as the adoption isotherms of mixtures. The model prediction was compared with the available experimental data, which shows that the predictions are reliable for most of the systems studied in this work. The effect of the pore size distribution on the model performance was further investigated, and it was found that the consideration of the pore size distribution (PSD) can improve the accuracy of the model results but the PSD analysis requires much more computing time.

Gulou Shen; Xiaohua Lu; Xiaoyan Ji

2014-01-01T23:59:59.000Z

209

Population Transfer between Two Quantum States by Piecewise Chirping of Femtosecond Pulses: Theory and Experiment  

SciTech Connect

We propose and experimentally demonstrate the method of population transfer by piecewise adiabatic passage between two quantum states. Coherent excitation of a two-level system with a train of ultrashort laser pulses is shown to reproduce the effect of an adiabatic passage, conventionally achieved with a single frequency-chirped pulse. By properly adjusting the amplitudes and phases of the pulses in the excitation pulse train, we achieve complete and robust population transfer to the target state. The piecewise nature of the process suggests a possibility for the selective population transfer in complex quantum systems.

Zhdanovich, S. [Departments of Physics and Astronomy, University of British Columbia, Vancouver (Canada); Laboratory for Advanced Spectroscopy and Imaging Research (LASIR), University of British Columbia, Vancouver (Canada); Shapiro, E. A. [Chemistry, University of British Columbia, Vancouver (Canada); Shapiro, M.; Hepburn, J. W.; Milner, V. [Departments of Physics and Astronomy, University of British Columbia, Vancouver (Canada); Chemistry, University of British Columbia, Vancouver (Canada); Laboratory for Advanced Spectroscopy and Imaging Research (LASIR), University of British Columbia, Vancouver (Canada)

2008-03-14T23:59:59.000Z

210

Session #1: Cutting Edge Methodologies--Beyond Current DFT  

NLE Websites -- All DOE Office Websites (Extended Search)

Session #1: Cutting Edge Methodologies (beyond Current DFT) Moderator: Shengbai Zhang (RPI/ REL) Topics to be addressed: Benchmarking state-of-the-art approaches, accurate energy landscape. Identify problems with the current DFT-LDA and GGA approaches and possible pathways to overcome these problems. PBE PBE How Bad is DFT for vdW Interactions? fcc Ar Benzene 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, Kohn � Fully nonlocal � functional: � � Long-range nonlocal correlation energy functional (omitted in the LDA and GGA) ) ( � Computational cost considerably more than GGA � Added as post-GGA energy correction but force

211

Session #1: Cutting Edge Methodologies--Beyond Current DFT  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

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,...

212

Theory of Multiple-Quantum Transitions in the Ground State of K30  

Science Journals Connector (OSTI)

The results of an earlier paper are applied to magnetic resonance transitions in the ground state of K39. Formulas are obtained for the parameters characterizing single- and multiple-quantum transitions, and the values of these parameters are calculated for a Zeeman field corresponding to x=0.21135.

Harold Salwen

1956-01-15T23:59:59.000Z

213

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

E-Print Network (OSTI)

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

Chu, Shih-I

214

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

E-Print Network (OSTI)

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

Baer, Roi

215

Extending the predictive power and scope of electronic structure theory and quantum transport  

E-Print Network (OSTI)

The day 1998 Nobel Prize recipient Walter Kohn wrote his first article on Density Functional Theory, he could never have predicted its eventual impact on computational materials science. Almost 50 years after his original ...

Poilvert, Nicolas (Nicolas Alain Pierre-Yves)

2011-01-01T23:59:59.000Z

216

Transitivity vs. Intransitivity in decision making process. (An example in quantum game theory)  

E-Print Network (OSTI)

We compare two different ways of quantization a simple sequential game Cat's Dilemma in the context of the debate on intransitive and transitive preferences. This kind of analysis can have essential meaning for the research on the artificial intelligence (some possibilities are discussed). Nature has both properties transitive and intransitive and maybe quantum models can be more able to capture this dualism than classical one. We also present electoral interpretation of the game.

Marcin Makowski

2009-01-12T23:59:59.000Z

217

Quantum Theory of Transmission Line Resonator-Assisted Cooling of a Micromechanical Resonator  

E-Print Network (OSTI)

We propose a quantum description of the cooling of a micromechanical flexural oscillator by a one-dimensional transmission line resonator via a force that resembles cavity radiation pressure. The mechanical oscillator is capacitively coupled to the central conductor of the transmission line resonator. At the optimal point, the micromechanical oscillator can be cooled close to the ground state, and the cooling can be measured by homodyne detection of the output microwave signal.

Yong Li; Ying-Dan Wang; Fei Xue; C. Bruder

2008-04-30T23:59:59.000Z

218

Quantum theory of optical temporal phase and instantaneous frequency. II. Continuous-time limit and state-variable approach to phase-locked loop design  

SciTech Connect

We consider the continuous-time version of our recently proposed quantum theory of optical temporal phase and instantaneous frequency [M. Tsang et al., Phys. Rev. A 78, 053820 (2008)]. Using a state-variable approach to estimation, we design homodyne phase-locked loops that can measure the temporal phase with quantum-limited accuracy. We show that postprocessing can further improve the estimation performance if delay is allowed in the estimation. We also investigate the fundamental uncertainties in the simultaneous estimation of harmonic-oscillator position and momentum via continuous optical phase measurements from the classical estimation theory perspective. In the case of delayed estimation, we find that the inferred uncertainty product can drop below that allowed by the Heisenberg uncertainty relation. Although this result seems counterintuitive, we argue that it does not violate any basic principle of quantum mechanics.

Tsang, Mankei; Shapiro, Jeffrey H. [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Lloyd, Seth [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2009-05-15T23:59:59.000Z

219

Theory of the reentrant quantum rotational phase transition in high-pressure HD  

Science Journals Connector (OSTI)

The phase diagram of HD near 50 GPa exhibits a reentrant phase transition where a rotationally ordered (broken symmetry) crystalline phase surprisingly transforms into a rotationally disordered high-symmetry phase upon cooling. The qualitative reason for reentrance is the higher entropy of the broken symmetry phase, due to the inequivalence of H and D, as opposed to the low entropy of the high-symmetry phase where the rotational melting is quantum mechanicala Pomeranchuk-like mechanism. Aiming at a quantitative understanding of this system, we present path integral Monte Carlo (MC) constant-pressure calculations for HD based on empirical but very realistic intermolecular interactions. Ignoring quantum mechanics at first, we use a metadynamics-based classical MC method to seek the lowest-energy zero-temperature classical state, which we identify as a very similar hcp-based structure C2/c as hypothesized by Surh et al. [Phys. Rev. B 55, 11330 (1997)]. Upon turning quantum rotational effects on, we calculate the pressure-temperature phase diagram by monitoring a lattice biased order parameter, and find a reentrant phase boundary in good agreement with experiment. The entropy jump across the transition is found to be comparable with ln2, the value expected for a Pomeranchuk mechanism. A comparison with earlier studies is also presented, yielding relevant information about the role of factors that quantitatively determine the reentrant part of the phase diagram.

Yanier Crespo; Alessandro Laio; Giuseppe E. Santoro; Erio Tosatti

2011-10-28T23:59:59.000Z

220

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

E-Print Network (OSTI)

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

Song, Xueyu

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


221

Weak value amplification: a view from quantum estimation theory that highlights what it is and what isn't  

E-Print Network (OSTI)

Weak value amplification, a 25 five years old technique used in metrology applications, has proved to be highly successful for measuring extremely tiny changes of a variable of interest. In spite of this, in what sense the technique is useful is still a question of debate. Here we show, making use of simple ideas taken from quantum estimation theory, what is the main contribution of the concept of weak value amplification to metrology. On the one hand, since the technique makes use of linear-optics unitary operations, it cannot modify the statistics of photons involved, and therefore, its capabilities are still fundamentally limited by the quantum nature of the light used. On the other hand, in certain scenarios weak value amplification can effectively enhance the sensitivity of real non-ideal detection schemes that might be limited by many other things apart from the specific characteristics of the light, i.e. technical noise. Importantly, it can do that in a straightforward and easily accessible manner.

Juan P. Torres; Luis Jose Salazar-Serrano

2014-08-08T23:59:59.000Z

222

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

E-Print Network (OSTI)

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

Ceder, Gerbrand

223

Quantum theory of a micromaser operating on the atomic scattering from a resonant standing wave  

E-Print Network (OSTI)

. Rev. Lett. 54, 551 ~1985!. @2# S. Haroche and J. M. Raimond, in Advances in Atomic and Molecular Physics, edited by D. R. Bates and B. Bederson ~Academics, New York, 1985!, Vol. 20, p. 350. @3# K. An, J.J. Childs, R.R. Dasari, and M.S. Feld, Phys...-of-mass motio DOI: 10.1103/PhysRevA.64.043812 I. INTRODUCTION Experimental realization of micromasers @1?3# has set the stage to comprehend the fundamental concepts, such as com- plimentarity and the nonlocal nature of the quantum world. In recent years...

Saif, F.; Le Kien, F.; Zubairy, M. Suhail

2001-01-01T23:59:59.000Z

224

Belief revision in quantum decision theory: gambler's and hot hand fallacies  

E-Print Network (OSTI)

In the present article we introduce a quantum mechanism which is able to describe the creation of correlations in the evaluation of random independent events: such correlations, known as positive and negative recency, correspond respectively to the hot hand's and to the gambler's fallacies. Thus we propose a description of these effects in terms of qubits, which may become entangled, forming a system which can not be described completely only in terms of its constituents. We show that such formalism is able to describe and interpret the experimental results, thus providing a general and unifying framework for the cognitive heuristics.

Riccardo Franco

2008-01-29T23:59:59.000Z

225

Theory of Linear Optical Absorption in Diamond Shaped Graphene Quantum Dots  

E-Print Network (OSTI)

In this paper, optical and electronic properties of diamond shaped graphene quantum dots (DQDs) have been studied by employing large-scale electron-correlated calculations. The computations have been performed using the $\\pi$-electron Pariser-Parr-Pople model Hamiltonian, which incorporates long-range Coulomb interactions. The influence of electron-correlation effects on the ground and excited states has been included by means of the configuration-interaction approach, used at various levels. Our calculations have revealed that the absorption spectra are red-shifted with the increasing sizes of quantum dots. It has been observed that the first peak of the linear optical absorption, which represents the optical gap, is not the most intense peak. This result is in excellent agreement with the experimental data, but in stark contrast to the predictions of the tight-binding model, according to which the first peak is the most intense peak, pointing to the importance of electron-correlation effects. Furthermore, a...

Basak, Tista; Shukla, Alok

2015-01-01T23:59:59.000Z

226

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

E-Print Network (OSTI)

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

Wu, Zhigang

227

Generalization of the Activated Complex Theory of Reaction Rates. I. Quantum Mechanical Treatment  

DOE R&D Accomplishments (OSTI)

In its usual form activated complex theory assumes a quasi-equilibrium between reactants and activated complex, a separable reaction coordinate, a Cartesian reaction coordinate, and an absence of interaction of rotation with internal motion in the complex. In the present paper a rate expression is derived without introducing the Cartesian assumption. The expression bears a formal resemblance to the usual one and reduces to it when the added assumptions of the latter are introduced.

Marcus, R. A.

1964-00-00T23:59:59.000Z

228

Theory of substrate, Zeeman, and electron-phonon interaction effects on the quantum capacitance in graphene  

SciTech Connect

Since the discovery of graphene, a lot of interest has been attracted by the zeroth Landau level, which has no analog in the conventional two dimensional electron gas. Recently, lifting of the spin and valley degeneracies has been confirmed experimentally by capacitance measurements, while in transport experiments, this is difficult due to the scattering in the device. In this context, we model interaction effects on the quantum capacitance of graphene in the presence of a perpendicular magnetic field, finding good agreement with experiments. We demonstrate that the valley degeneracy is lifted by the substrate and by Kekule distortion, whereas the spin degeneracy is lifted by Zeeman interaction. The two cases can be distinguished by capacitance measurements.

Tahir, M. [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Sabeeh, K. [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Shaukat, A. [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Schwingenschlgl, U., E-mail: Udo.Schwingenschlogl@kaust.edu.sa [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia)

2013-12-14T23:59:59.000Z

229

Multi-channel conduction in redox-based resistive switch modelled using quantum point contact theory  

SciTech Connect

A simple analytic model for the electron transport through filamentary-type structures in Si-rich silica (SiO{sub x})-based resistive switches is proposed. The model is based on a mesoscopic description and is able to account for the linear and nonlinear components of conductance that arise from both fully and partially formed conductive channels spanning the dielectric film. Channels are represented by arrays of identical scatterers whose number and quantum transmission properties determine the current magnitude in the low and high resistance states. We show that the proposed model not only reproduces the experimental current-voltage (I-V) characteristics but also the normalized differential conductance (dln(I)/dln(V)-V) curves of devices under test.

Miranda, E., E-mail: enrique.miranda@uab.cat; Su, J. [Departament d'Enginyeria Electrnica, Universitat Autnoma de Barcelona, 08193 Cerdanyola del Valls, Barcelona (Spain)] [Departament d'Enginyeria Electrnica, Universitat Autnoma de Barcelona, 08193 Cerdanyola del Valls, Barcelona (Spain); Mehonic, A.; Kenyon, A. J. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)] [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

2013-11-25T23:59:59.000Z

230

Amplitudes in the N=4 supersymmetric Yang-Mills theory from quantum geometry of momentum space  

SciTech Connect

We discuss multiloop maximally helicity violating amplitudes in the N=4 supersymmetric Yang-Mills theory in terms of effective gravity in the momentum space with IR regulator branes as degrees of freedom. Kinematical invariants of external particles yield the moduli spaces of complex or Kahler structures which are the playgrounds for the Kodaira-Spencer or Kahler type gravity. We suggest fermionic representation of the loop maximally helicity violating amplitudes in the N=4 supersymmetric Yang-Mills theory assuming the identification of the IR regulator branes with Kodaira-Spencer fermions in the B model and Lagrangian branes in the A model. The two-easy mass box diagram is related to the correlator of fermionic currents on the spectral curve in the B model or hyperbolic volume in the A model and it plays the role of a building block in the whole picture. The Bern-Dixon-Smirnov-like ansatz has the interpretation as the semiclassical limit of a fermionic correlator. It is argued that fermionic representation implies a kind of integrability on the moduli spaces. We conjecture the interpretation of the reggeon degrees of freedom in terms of the open strings stretched between the IR regulator branes.

Gorsky, A. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, Moscow, 117259 (Russian Federation)

2009-12-15T23:59:59.000Z

231

Helium under high pressure: A comparative study of all-electron and pseudopotential methods within density functional theory  

E-Print Network (OSTI)

We have calculated the ground state electronic structure of He under pressure from 0 to 1500 GPa using both all-electron full-potential and pseudopotential methods based on the density functional theory (DFT). We find that throughout this pressure range, pseudopotentials yield essentially the same energy-volume curve for all of bcc, fcc, and hcp configurations as does the full-potential method, a strong indication that pseudopotential approximation works well for He both as the common element in some giant planets and as detrimental impurities in fusion reactor materials. The hcp lattice is always the most stable structure and bcc the least stable one. Since the energy preference of hcp over fcc and bcc is within 0.01 eV below 100 GPa and about 0.1 eV at 1500 GPa, on the same order of the error bar in local or semi-local density approximations in DFT, phase transitions can only be discussed with more precise description of electron correlation in Quantum Monte Carlo or DFT-based GW methods.

Xiao, W; Geng, W T

2012-01-01T23:59:59.000Z

232

Physics as Quantum Information Processing: Quantum Fields as Quantum Automata  

E-Print Network (OSTI)

Can we reduce Quantum Field Theory (QFT) to a quantum computation? Can physics be simulated by a quantum computer? Do we believe that a quantum field is ultimately made of a numerable set of quantum systems that are unitarily interacting? A positive answer to these questions corresponds to substituting QFT with a theory of quantum cellular automata (QCA), and the present work is examining this hypothesis. These investigations are part of a large research program on a "quantum-digitalization" of physics, with Quantum Theory as a special theory of information, and Physics as emergent from the same quantum-information processing. A QCA-based QFT has tremendous potential advantages compared to QFT, being quantum "ab-initio" and free from the problems plaguing QFT due to the continuum hypothesis. Here I will show how dynamics emerges from the quantum processing, how the QCA can reproduce the Dirac-field phenomenology at large scales, and the kind of departures from QFT that that should be expected at a Planck-scale discreteness. I will introduce the notions of linear field quantum automaton and local-matrix quantum automaton, in terms of which I will provide the solution to the Feynman's problem about the possibility of simulating a Fermi field with a quantum computer.

Giacomo Mauro D'Ariano

2011-10-31T23:59:59.000Z

233

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

SciTech Connect

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

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

2013-11-28T23:59:59.000Z

234

Analyzing Data Streams by Online DFT Alexander Hinneburg1  

E-Print Network (OSTI)

University of Technology, Germany dirk.habich@tu-dresden.de 3 Technical University of Ilmenau, Germany marcel Martin-Luther University of Halle-Wittenberg, Germany hinneburg@informatik.uni-halle.de 2 Dresden DFT lead to a number of interesting applications, e.g., forecasting, clean- ing, and moni

Hinneburg, Alexander

235

Electronic Spectra and DFT Calculations of Hexanuclear Chalcocyanide Rhenium Clusters  

Science Journals Connector (OSTI)

Electronic Spectra and DFT Calculations of Hexanuclear Chalcocyanide Rhenium Clusters ... The good agreement with experiment obtained for the geometrical parameters gives the basis for comparing the calculated electronic transitions of these complexes with the experimental electronic spectra. ... On the calculation of bonding energies by the Hartree Fock Slater method. ...

S. G. Kozlova; S. P. Gabuda; K. A. Brylev; Yu. V. Mironov; V. E. Fedorov

2004-11-03T23:59:59.000Z

236

Can a "Hidden Variable'' Quantum Theory Evade the "No-Cloning" Theorem?  

E-Print Network (OSTI)

If YES, then we can look forward to physical realization of superluminal communication, as the original considerations of the ``no-cloning'' theorem were motivated in part as an explanation of why certain schemes for superluminal signaling cannot work. If NO, then it would seem that some aspects of the ``hidden'' variables must be ``intrinsically hidden'', i.e., ``unknowable'', such that ``hidden-variable'' theories belong more to the ``idealist'' than to the ``realist'' school of thought. I pose this question without proposing a definite answer. I am unaware of any commentary on this topic during these 23 years since the formulation of the ``no-cloning'' theorem, but I would be pleased to be enlightened by more knowledgeable readers.

Kirk T. McDonald

2005-10-06T23:59:59.000Z

237

Electronic structure calculations of PbS quantum rods and tubes  

SciTech Connect

We study absorption spectra, optical and HOMO-LUMO gaps, and the density of states for PbS quantum rods (QRs) and tubes (QTs). We find some similarities and also differences in QR and QT properties. For both QRs and QTs, the optical and HOMO-LUMO gaps reach the plateaus for small lengths. We find that tubes are as stable as rods. The optical spectra exhibit a peak that can be due to the electron-hole interaction or be a prototype of an S{sub e}S{sub h} transition in the effective mass approximation. We also calculate the density of states by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The TDDFT density of states function is shifted towards the red side by 0.5?eV indicating the strong e-h interaction.

Pimachev, Artem; Dahnovsky, Yuri, E-mail: yurid@uwyo.edu [Department of Physics and Astronomy/3905, 1000 E. University Avenue, University of Wyoming Laramie, Wyoming 82071 (United States)

2014-01-28T23:59:59.000Z

238

Quantum dynamics with fermion coupled coherent states: Theory and application to electron dynamics in laser fields  

SciTech Connect

We present an alternate version of the coupled-coherent-state method, specifically adapted for solving the time-dependent Schroedinger equation for multielectron dynamics in atoms and molecules. This theory takes explicit account of the exchange symmetry of fermion particles, and it uses fermion molecular dynamics to propagate trajectories. As a demonstration, calculations in the He atom are performed using the full Hamiltonian and accurate experimental parameters. Single- and double-ionization yields by 160-fs and 780-nm laser pulses are calculated as a function of field intensity in the range 10{sup 14}-10{sup 16} W/cm{sup 2}, and good agreement with experiments by Walker et al. is obtained. Since this method is trajectory based, mechanistic analysis of the dynamics is straightforward. We also calculate semiclassical momentum distributions for double ionization following 25-fs and 795-nm pulses at 1.5x10{sup 15} W/cm{sup 2}, in order to compare them with the detailed experiments by Rudenko et al. For this more challenging task, full convergence is not achieved. However, major effects such as the fingerlike structures in the momentum distribution are reproduced.

Kirrander, Adam [Laboratoire Aime Cotton du CNRS, Universite de Paris-Sud, Batiment 505, F-91405 Orsay (France); Shalashilin, Dmitrii V. [School of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom)

2011-09-15T23:59:59.000Z

239

First principles DFT investigation of yttrium-doped graphene: Electronic structure and hydrogen storage  

SciTech Connect

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.

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

240

Dynamic local-field factor of an electron liquid in the quantum versions of the Singwi-Tosi-Land-Sjlander and Vashishta-Singwi theories  

Science Journals Connector (OSTI)

We have investigated in detail the complex, dynamic local field G(q,?) of an electron liquid in the quantum versions of the Singwi-Tosi-Land-Sjlander (STLS) and Vashishta-Singwi (VS) theories. We have worked out the various analytical properties of G(q,?) and shown that the STLS and VS theories are the high-frequency limits of the quantum cases. Variation of G(q,?) with ? is found to be rather mild. Interestingly, the static local field G(q,0) exhibits, in the region of metallic densities, a peaked structure around q?2.8kF, in contrast to the monotonically increasing local-field factors of the STLS and VS theories. The height of the peak reaches values greater than 1, which causes the effective particle-hole interaction to become attractive. This gives rise to the possibility of a charge-density-wave instability. We also give a parametric representation of G(q,0), which fulfills exactly the compressibility sum rule.

A. Holas and Shafiqur Rahman

1987-02-15T23:59:59.000Z

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


241

Structural and Energetic Analysis of MgxM1?x(OH)2 (M = Zn, Cu or Ca) Brucite-Like Compounds by DFT Calculations  

Science Journals Connector (OSTI)

Structural and Energetic Analysis of MgxM1?x(OH)2 (M = Zn, Cu or Ca) Brucite-Like Compounds by DFT Calculations ... Brucite-like mixed hydroxides of the general formula MgxM1?x(OH)2 for M = Zn, Cu or Ca were studied by density functional theory within pseudopotential approximation, plane waves basis set, and periodic boundary conditions. ... Brucite, which is the mineral form of magnesium hydroxide, is a commonly occurring material. ...

Deyse G. Costa; Alexandre B. Rocha; Wladmir F. Souza; Sandra Shirley X. Chiaro; Alexandre A. Leito

2008-06-28T23:59:59.000Z

242

THE MANY-ELECTRON ENERGY IN DENSITY FUNCTIONAL THEORY  

E-Print Network (OSTI)

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

Armiento, Rickard

243

RELATIVISTIC DENSITY FUNCTIONAL THEORY: FOUNDATIONS AND BASIC FORMALISM  

E-Print Network (OSTI)

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

Engel, Eberhard

244

Publisher's Note: Correlation of photon pairs from the double Raman amplifier: Generalized analytical quantum Langevin theory (vol 75, pg 013820, 2007)  

E-Print Network (OSTI)

Publisher?s Note: Correlation of photon pairs from the double Raman amplifier: Generalized analytical quantum Langevin theory [Phys. Rev. A 75, 013820 (2007)] C. H. Raymond Ooi, Qingqing Sun, M. Suhail Zubairy, and Marlan O. Scully #1;Received 1... February 2007; published 6 February 2007#2; DOI: 10.1103/PhysRevA.75.029902 PACS number#1;s#2;: 42.50.Dv, 42.50.Gy, 42.50.Lc, 03.67.Mn, 99.10.Fg This paper was published online on 31 January 2007 without all of the author?s corrections incorporated...

Ooi, C. H. Raymond; Sun, Qingqing; Zubairy, M. Suhail; Scully, Marlan O.

2007-01-01T23:59:59.000Z

245

Extended Coulomb approximation for multichannel-quantum-defect-theory computations of dipole moments:?Method of calculation and application to H2  

Science Journals Connector (OSTI)

A method for calculating dipole transition moments in effective one-electron systems when some channels are closed is investigated within the framework of multichannel quantum-defect theory (MQDT). A treatment of the energy dependence is also given. This method is useful when electronic channel interactions occur and MQDT is combined with frame transformations. Our calculations are made in the Coulomb approximation and include provisions for core transitions. They are tested by comparing transitions between bound states of molecular hydrogen with ab initio computations.

A. Matzkin; Ch. Jungen; S. C. Ross

1998-12-01T23:59:59.000Z

246

Functionalized Graphene Nanoroads for Quantum Well Device. |...  

NLE Websites -- All DOE Office Websites (Extended Search)

Nanoroads for Quantum Well Device. Functionalized Graphene Nanoroads for Quantum Well Device. Abstract: Using density functional theory, a series of calculations of structural and...

247

E-Print Network 3.0 - approximate dft method Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

D'Alberto Yahoo pdalbert@yahoo-inc.com Peter A... - tions of the discrete Fourier transform (DFT) in fixed point precision. The partitioning strategy Source: Moura, Jos -...

248

Theory of optical properties of II-VI semiconductor quantum dots containing a single magnetic ion in a strong magnetic field  

Science Journals Connector (OSTI)

We present a microscopic theory of the magnetic field dependence of the optical properties of IIVI semiconductor quantum dots containing a single magnetic (Mn) impurity. The single-particle electron and heavy-hole states are described exactly by two-dimensional harmonic oscillators in a magnetic field, the Mn ion is treated as a spin of an isoelectronic impurity, and the quantum dot anisotropy is included perturbatively. The electron-hole direct, short-, and long-range exchange electron-hole Coulomb interactions, as well as the short-range spin-spin contact exchange interaction of the electron and the hole with the magnetic impurity is included. The electron-hole-Mn states are expanded in a finite number of configurations controlled by the number of confined electronic quantum dot shells and the full interacting Hamiltonian is diagonalized numerically in this basis. The absorption and emission spectrum is predicted as a function of photon energy, magnetic field, number of confined shells, and anisotropy. It is shown that the magnetic-field-induced enhancement of the exchange interaction of the Mn spin with the exciton is largely canceled by increased electron-hole Coulomb interactions. The predicted weak magnetic field dependence of the spacing of emission lines agrees well with the results of the spin model at low magnetic fields but differs at higher magnetic fields. Correlations in the exciton-Mn complex are predicted to determine absorption spectra.

Anna H. Trojnar; Marek Korkusi?ski; Marek Potemski; Pawel Hawrylak

2012-04-06T23:59:59.000Z

249

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

E-Print Network (OSTI)

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

Bertsch George F.

250

Theory of two-dimensional macroscopic quantum tunneling in a Josephson junction coupled with an LC circuit  

E-Print Network (OSTI)

We investigate classical thermal activation (TA) and macroscopic quantum tunneling (MQT) for a Josephson junction coupled with an LC circuit theoretically. The TA and MQT escape rate are calculated analytically by taking into account the two-dimensional nature of the classical and quantum phase dynamics. We find that the MQT escape rate is largely suppressed by the coupling to the LC circuit. On the other hand, this coupling gives rise to slight reduction of the TA escape rate. These results are relevant for the interpretation of a recent experiment on the MQT and TA phenomena in grain boundary YBCO Josephson junctions.

Shiro Kawabata; Takeo Kato; Thilo Bauch

2009-12-17T23:59:59.000Z

251

PHYSICAL REVIEW B 89, 224507 (2014) Theory of macroscopic quantum tunneling with Josephson-Leggett collective excitations  

E-Print Network (OSTI)

-Leggett collective excitations in multiband superconducting Josephson junctions Hidehiro Asai,1,* Yukihiro Ota,2) in a Josephson junction composed of multiband superconductors, focusing on a phase mode induced by interband I. INTRODUCTION Josephson junctions show phenomena caused by macroscopic-scale quantum coherence

Nori, Franco

252

Putting DFT to the Test: A First Principles Study of Electronic, Magnetic and Optical Properties of Co3O4  

Science Journals Connector (OSTI)

Putting DFT to the Test: A First Principles Study of Electronic, Magnetic and Optical Properties of Co3O4 ...

Vijay Singh; Monica Kosa; Koushik Majhi; Dan Thomas Major

2014-11-25T23:59:59.000Z

253

Observer Localization in Multiverse Theories Marcus Hutter  

E-Print Network (OSTI)

battle; and the ongoing discussion of whether string theory is a theory of everything or more a theory's oscillating universe, Smolin's baby universe theory, Everett's many-worlds interpretation of quantum mechanics

Hutter, Marcus

254

Changing quantum reference frames  

E-Print Network (OSTI)

We consider the process of changing reference frames in the case where the reference frames are quantum systems. We find that, as part of this process, decoherence is necessarily induced on any quantum system described relative to these frames. We explore this process with examples involving reference frames for phase and orientation. Quantifying the effect of changing quantum reference frames serves as a first step in developing a relativity principle for theories in which all objects including reference frames are necessarily quantum.

Matthew C. Palmer; Florian Girelli; Stephen D. Bartlett

2014-05-21T23:59:59.000Z

255

Hybrid DFT Functional-Based Static and Molecular Dynamics Studies of Excess Electron in Liquid Ethylene Carbonate  

SciTech Connect

We applied static and dynamic hybrid functional density functional theory (DFT) calculations to study the interactions of one and two excess electrons with ethylene carbonate (EC) liquid and clusters. Optimal structures of (EC){sub n} and (EC){sup ?}{sub n} clusters devoid of Li{sub +} ions, n?=?16, were obtained. The excess electron was found to be localized on a single EC in all cases, and the EC dimeric radical anion exhibits a reduced barrier associated with the breaking of the ethylene carbonoxygen covalent bond compared to EC{sub ?}. In ab initio molecular dynamics (AIMD) simulations of EC{sub ?} solvated in liquid EC, large fluctuations in the carbonyl carbonoxygen bond lengths were observed. AIMD simulations of a two-electron attack on EC in EC liquid and on Li metal surfaces yielded products similar to those predicted using nonhybrid DFT functionals, except that CO release did not occur for all attempted initial configurations in the liquid state.

Yu, J M; Balbuena, P B; Budzien, J L; Leung, Kevin

2011-01-01T23:59:59.000Z

256

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

SciTech Connect

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

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

2011-01-01T23:59:59.000Z

257

EERE PROJECT MANAGEMENT CENTER NFPA DFT1!lUIINATION  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

OFEN:rRGY OFEN:rRGY EERE PROJECT MANAGEMENT CENTER NFPA DFT1!lUIINATION Page 1 of2 RECIPIENT:Middlesex Community College STATE: MA PROJECf TITLE: Middlesex Community College - Geothermal Project Funding Opportunity Announcement Number Procurement Instrument Number NEPA Control Number CID Number N/A DE-EEOOOO323 GF0-0000323-002 EE323 Based on my review ofthe information concerning the proposed action, as NEPA Compliance Officer (authorized under DOE Order 4SI.IA), I have made the following determination: ex, EA, EIS APPENDIX AND NUMBER: Description: A9 Inf ormation gathering, analYSiS, and dissemination 82.1 Workplace enhancements B2.2 Building and equipment instrumentation Information gathering (including, but not limited to, literature surveys, inventories, site visits, and audils),

258

Magnetotransport theory in quantum dots: 3D-0D and 2D-0D tunneling and angular momentum selection rules  

Science Journals Connector (OSTI)

A study of magnetotransport through quantum dots is presented. The model allows one to analyze tunneling both from bulk-like contacts and from 2D accumulation layers. The fine features in the I-V characteristics due to the quantum dot states are known to be shifted to different voltages depending upon the value of the magnetic field. While this effect is also well reproduced by our calculations, in this work we concentrate on the amplitude of each current resonance as a function of the magnetic field. Such amplitudes show oscillations reflecting the variation of the density of states at the Fermi energy in the emitter. Furthermore the amplitude increases as a function of the magnetic field for certain features while it decreases for others. In particular, we demonstrate that the behavior of the amplitude of the current resonances is linked to the value of the angular momentum of each dot level through which tunneling occurs. We show that a selection rule on the angular momentum must be satisfied. As a consequence, tunneling through specific dot states is strongly suppressed and sometimes prohibited altogether by the presence of the magnetic field. This will allow to extract from the experimental curves detailed information on the nature of the quantum-dot wave functions involved in the electronic transport. Furthermore, when tunneling occurs from a two-dimensional accumulation layer to the quantum dot, the presence of a magnetic field hugely increases the strength of some resonant features. This effect is predicted by our model and, to the best of our knowledge, has never been observed.

B. Jouault; M. Boero; G. Faini; J. C. Inkson

1999-02-15T23:59:59.000Z

259

Quantum Monte Carlo calculations of electromagnetic moments and transitions in A{<=}9 nuclei including meson-exchange currents derived from chiral effective field theory  

SciTech Connect

Quantum Monte Carlo calculations of electromagnetic moments and transitions are reported for A{<=}9 nuclei. The realistic Argonne v{sub 18} two-nucleon and Illinois-7 three-nucleon potentials are used to generate the nuclear wave functions. Contributions of two-body meson-exchange current (MEC) operators are included for magnetic moments and M1 transitions. The MEC operators have been derived in both a standard nuclear physics approach and a chiral effective field theory formulation with pions and nucleons including up to one-loop corrections. The two-body MEC contributions provide significant corrections and lead to very good agreement with experiment. Their effect is particularly pronounced in the A=9, T=3/2 systems, in which they provide up to ~20% (~40%) of the total predicted value for the {sup 9}Li ({sup 9}C) magnetic moment.

Saori Pastore, S.C. Pieper, Rocco Schiavilla, Robert Wiringa

2013-03-01T23:59:59.000Z

260

Time in quantum mechanics  

E-Print Network (OSTI)

OF CONTENTS I. INTRODUCTION II. HISTORICAL DEVELOPMENT A. Classical Mechanics B. Quantum Theory . C. The Problem 3 4 6 III. TIME ATOMS AND DISCRETE TIME A. The Earliest Applications of Atomistic and Discrete Time . . . . . B. The Radiating Electron... . C. Quantum Field Theory 8 10 l2 IV. TIME OPERATOR FORMULATIONS 16 A. Advocates Against a Time Operator . B. The Possibility of a Time Operator C, Advocates in Favor of a Time Operator D. A Restricted Time Delay Operator: Scattering Theory...

Chapin, Kimberly R.

2012-06-07T23:59:59.000Z

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


261

Physics as Information Theory  

SciTech Connect

The experience from Quantum Information of the last twenty years has lead theorists to look at Quantum Theory and the whole of Physics from a different angle. A new information-theoretic paradigm is emerging, long time ago prophesied by John Archibald Wheeler with his popular coinage 'It from bit'. Theoretical groups are now addressing the problem of deriving Quantum Theory from informational principles, and similar lines are investigated in new approaches to Quantum Gravity. In my talk I will review some recent advances on these lines. The general idea synthesizing the new paradigm is that there is only Quantum Theory (without quantization rules): the whole Physics--including space-time and relativity--is emergent from quantum-information processing. And, since Quantum Theory itself is made with purely informational principles, the whole Physics must be reformulated in information-theoretical terms. The review is divided into the following parts: (a) The informational axiomatization of Quantum Theory; (b) How space-time and relativistic covariance emerge from the quantum computation; (c) What is the information-theoretical meaning of inertial mass and Planck constant, and how the quantum field emerges; (d) Observational consequences: mass-dependent refraction index of vacuum. I then conclude with some possible future research lines.

D'Ariano, Giacomo Mauro (University of Pavia) [University of Pavia

2010-10-20T23:59:59.000Z

262

Interfacial tension of nonassociating pure substances and binary mixtures by density functional theory combined with PengRobinson equation  

E-Print Network (OSTI)

of the existing DFT versions can be reduced to the statistical associating fluid theory SAFT and its derivatives.6­11 Unfortunately, SAFT has not been widely used in petroleum production and reservoir engineering cal- culations

Firoozabadi, Abbas

263

Generalized quantum defect methods in quantum chemistry  

E-Print Network (OSTI)

The reaction matrix of multichannel quantum defect theory, K, gives a complete picture of the electronic structure and the electron - nuclear dynamics for a molecule. The reaction matrix can be used to examine both bound ...

Altunata, Serhan

2006-01-01T23:59:59.000Z

264

Electronic structure and excitations in oxygen deficient CeO2?? from DFT calculations  

Science Journals Connector (OSTI)

The electronic structures of supercells of CeO2?? have been calculated within the density functional theory (DFT). The equilibrium properties such as lattice constants, bulk moduli, and magnetic moments are well reproduced by the generalized gradient approximation (GGA). Electronic excitations are simulated by robust total-energy calculations for constrained states with atomic core holes or valence holes. Pristine ceria CeO2 is found to be a nonmagnetic insulator with magnetism setting in as soon as oxygens are removed from the structure. In the ground state of defective ceria, the Ce-f majority band resides near the Fermi level but appears at about 2eV below the Fermi level in photoemission spectroscopy experiments due to final-state effects. We also tested our computational method by calculating threshold energies in Ce-M5 and O-K x-ray absorption spectroscopy and comparing theoretical predictions with the corresponding measurements. Our result that f electrons reside near the Fermi level in the ground state of oxygen-deficient ceria is crucial for understanding the catalytic properties of CeO2 and related materials.

T. Jarlborg; B. Barbiellini; C. Lane; Yung Jui Wang; R. S. Markiewicz; Zhi Liu; Zahid Hussain; A. Bansil

2014-04-01T23:59:59.000Z

265

Methanol Synthesis from CO2 Hydrogenation over a Pd4/In2O3 Model Catalyst: A Combined DFT and Kinetic Study  

SciTech Connect

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.

Ye, Jingyun; Liu, Changjun; Mei, Donghai; Ge, Qingfeng

2014-08-01T23:59:59.000Z

266

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

E-Print Network (OSTI)

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

Lin, Xi

267

Moderately dense gas quantum kinetic theory: Aspects of pair correlations R. F. Snider and G. W. Wei  

E-Print Network (OSTI)

Boltzmann equation emphasizes the need to explicitly include pair correlations and the conversion of kinetic energy to potential energy as important effects in the kinetic theory of moderately dense gases that the pair density operator used for collisions should be such that it factors both before and after

Wei, Guo-Wei

268

Multicomponent density-functional theory for electrons and nuclei Thomas Kreibich  

E-Print Network (OSTI)

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

Gross, E.K.U.

269

On the Floquet formulation of time-dependent density functional theory  

E-Print Network (OSTI)

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

270

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

E-Print Network (OSTI)

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

Gross, E.K.U.

271

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

E-Print Network (OSTI)

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

Gross, E.K.U.

272

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

E-Print Network (OSTI)

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

Sun, Sean

273

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

E-Print Network (OSTI)

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

Lorin, Emmanuel

274

Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT  

SciTech Connect

We have investigated the description of excited state relaxation in naked and hydrated TiO2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be the inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. Finally, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO2 nanoparticles is predicted to be associated with a large Stokes shift.

Berardo, Enrico; Hu, Hanshi; van Dam, Hubertus JJ; Shevlin, S. A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

2014-10-30T23:59:59.000Z

275

DFT calculations on nitrodiborane compounds as new potential high energy materials  

Science Journals Connector (OSTI)

We have used DFT methods to determine the structures and thermochemistry of several nitro-substituted diborane molecules in an attempt to rate their potential as high energy materials. The properties of nitrodibo...

John Abdelmalik; David W. Ball

2010-05-01T23:59:59.000Z

276

The Euler and Grace-Danielsson inequalities for nested triangles and tetrahedra: a derivation and generalisation using quantum information theory  

E-Print Network (OSTI)

We derive several results in classical Euclidean elementary geometry using the steering ellipsoid formalism from quantum mechanics. This gives a physically motivated derivation of very non-trivial geometric results, some of which are entirely new. We consider a sphere of radius $r$ contained inside another sphere of radius $R$, with the sphere centres separated by distance $d$. When does there exist a nested tetrahedron circumscribed about the smaller sphere and inscribed in the larger? We derive the Grace-Danielsson inequality $d^2 \\leq (R+r)(R-3r)$ as the sole necessary and sufficient condition for the existence of a nested tetrahedron. Our method also gives the condition $d^2 \\leq R(R-2r)$ for the existence of a nested triangle in the analogous 2-dimensional scenario. These results imply the Euler inequality in 2 and 3 dimensions. Furthermore, we formulate a new inequality that applies to the more general case of ellipses and ellipsoids.

Antony Milne

2014-06-26T23:59:59.000Z

277

Generalized SAFT-DFT/DMT Model for the Thermodynamic, Interfacial, and Transport Properties of Associating Fluids:? Application for n-Alkanols  

Science Journals Connector (OSTI)

Generalized SAFT-DFT/DMT Model for the Thermodynamic, Interfacial, and Transport Properties of Associating Fluids:? Application for n-Alkanols ... We have developed a global crossover (GC) statistical associating fluid theory (SAFT) equation of state (EOS) for associating fluids that incorporates nonanalytic scaling laws in the critical region and in the limit of low densities, ? ? 0, is transformed into the ideal-gas equation EOS. ... Unlike the crossover SAFT EOS developed earlier, the new GC SAFT EOS contains a so-called kernel term and reproduces the asymptotic scaling behavior of the isochoric heat capacity in the one- and two-phase regions. ...

S. B. Kiselev; J. F. Ely; I. M. Abdulagatov; M. L. Huber

2005-07-02T23:59:59.000Z

278

DFT calculations of EPR parameters of transition metal complexes: Implications for catalysis  

SciTech Connect

Transition metal and ligand hyperfine coupling constants for paramagnetic vanadium and copper model complexes have been calculated using DFT methods that are available in commercial software packages. Variations in EPR parameters with ligand identity and ligand orientation are two of the trends that have been investigated with DFT calculations. For example, the systematic variation of the vanadium hyperfine coupling constant with orientation for an imidazole ligand in a VO2+ complex has been observed experimentally and has also been reproduced by DFT calculations. Similarly, changes in the vanadium hyperfine coupling constant with ligand binding have been calculated using model complexes and DFT methods. DFT methods were also used to calculate ligand hyperfine coupling constants in transition metal systems. The variation of the proton hyperfine coupling constant with water ligand orientation was investigated for [VO(H2O)5]2+ and the results were used to interpret high resolution EPR data of VO2+-exchanged zeolites. Nitrogen hyperfine and quadrupole coupling constants for VO2+ model complexes were calculated and compared with experimental data. The computational results were used to enhance the interpretation of the EPR data for vanadium-exchanged zeolites which are promising catalytic materials. The implications of the DFT calculations of EPR parameters with respect to catalysis will be discussed

Saladino, Alexander C.; Larsen, Sarah C.

2005-07-15T23:59:59.000Z

279

Nested Quantum Error Correction Codes  

E-Print Network (OSTI)

The theory of quantum error correction was established more than a decade ago as the primary tool for fighting decoherence in quantum information processing. Although great progress has already been made in this field, limited methods are available in constructing new quantum error correction codes from old codes. Here we exhibit a simple and general method to construct new quantum error correction codes by nesting certain quantum codes together. The problem of finding long quantum error correction codes is reduced to that of searching several short length quantum codes with certain properties. Our method works for all length and all distance codes, and is quite efficient to construct optimal or near optimal codes. Two main known methods in constructing new codes from old codes in quantum error-correction theory, the concatenating and pasting, can be understood in the framework of nested quantum error correction codes.

Zhuo Wang; Kai Sun; Hen Fan; Vlatko Vedral

2009-09-28T23:59:59.000Z

280

Intrinsic point-defect equilibria in tetragonal ZrO[subscript 2]: Density functional theory analysis with finite-temperature effects  

E-Print Network (OSTI)

We present a density functional theory (DFT) framework taking into account the finite temperature effects to quantitatively understand and predict charged defect equilibria in a metal oxide. Demonstration of this approach ...

Youssef, Mostafa Youssef Mahm

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


281

Quantum Terahertz Electrodynamics and Macroscopic Quantum Tunneling in Layered Superconductors  

E-Print Network (OSTI)

of macroscopic quantum tunneling (MQT) in stacks of intrinsic Josephson junctions. Because of the long numbers: 74.72.Hs, 74.78.Fk The recent surge of interest in stacks of intrinsic Josephson junctions of stacks of Josephson junctions in quantum electronics [6]. This requires a quantum theory capable

Nori, Franco

282

Quantum Spacetime Phenomenology  

E-Print Network (OSTI)

I review the current status of phenomenological programs inspired by quantum-spacetime research. I stress in particular the significance of results establishing that certain data analyses provide sensitivity to effects introduced genuinely at the Planck scale. And my main focus is on phenomenological programs that managed to affect the directions taken by studies of quantum-spacetime theories.

Giovanni Amelino-Camelia

2013-06-18T23:59:59.000Z

283

Copenhagen Quantum Mechanics Emerges from a Deterministic Schroedinger Theory in 11 Dimensional Spacetime Including Weak Field Gravitation  

E-Print Network (OSTI)

We construct a world model consisting of a matter field living in 4 dimensional spacetime and a gravitational field living in 11 dimensional spacetime. The seven hidden dimensions are compactified within a radius estimated by reproducing the particle - wave characteristic of diffraction experiments. In the presence of matter fields the gravitational field develops localized modes with elementary excitations called gravonons which are induced by the sources (massive particles). The final world model treated here contains only gravonons and a scalar matter field. The solution of the Schroedinger equation for the world model yields matter fields which are localized in the 4 dimensional subspace. The localization has the following properties: (i) There is a chooser mechanism for the selection of the localization site. (ii) The chooser selects one site on the basis of minor energy differences and differences in the gravonon structure between the sites, which appear statistical. (iii) The changes from one localization site to a neighbouring one take place in a telegraph-signal like manner. (iv) The times at which telegraph like jumps occur dependent on subtleties of the gravonon structure which appear statistical. (v) The fact that the dynamical law acts in the configuration space of fields living in 11 dimensional spacetime lets the events observed in 4 dimensional spacetime appear non-local. In this way the phenomenology of Copenhagen quantum mechanics is obtained without the need of introducing the process of collapse and a probabilistic interpretation of the wave function. Operators defining observables need not be introduced. All experimental findings are explained in a deterministic way as a consequence of the time development of the wave function in configuration space according to Schroedinger's equation.

Gerold Doyen; Deiana Drakova

2014-08-12T23:59:59.000Z

284

Quantum Robot: Structure, Algorithms and Applications  

E-Print Network (OSTI)

A kind of brand-new robot, quantum robot, is proposed through fusing quantum theory with robot technology. Quantum robot is essentially a complex quantum system and it is generally composed of three fundamental parts: MQCU (multi quantum computing units), quantum controller/actuator, and information acquisition units. Corresponding to the system structure, several learning control algorithms including quantum searching algorithm and quantum reinforcement learning are presented for quantum robot. The theoretic results show that quantum robot can reduce the complexity of O(N^2) in traditional robot to O(N^(3/2)) using quantum searching algorithm, and the simulation results demonstrate that quantum robot is also superior to traditional robot in efficient learning by novel quantum reinforcement learning algorithm. Considering the advantages of quantum robot, its some potential important applications are also analyzed and prospected.

Dao-Yi Dong; Chun-Lin Chen; Chen-Bin Zhang; Zong-Hai Chen

2005-06-18T23:59:59.000Z

285

1 Elementary Quantum Chemistry In this introductory chapter we will review some of the fundamental aspects of electronic  

E-Print Network (OSTI)

discussion on density functional theory (DFT) presented in later parts of this book. Our exposition define the potential part of the Hamiltonian and repre- A Chemist's Guide to Density Functional Theory of the fundamental aspects of electronic structure theory in order to lay the foundations for the theoretical

Nielsen, Steven O.

286

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

E-Print Network (OSTI)

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

Thygesen, Kristian

287

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

E-Print Network (OSTI)

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

Ceder, Gerbrand

288

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

E-Print Network (OSTI)

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

Gross, E.K.U.

289

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

E-Print Network (OSTI)

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

Hess, Daryl W.

290

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

E-Print Network (OSTI)

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

Gross, E.K.U.

291

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

E-Print Network (OSTI)

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

Gross, E.K.U.

292

5.74 Introductory Quantum Mechanics II, Spring 2005  

E-Print Network (OSTI)

Time-dependent quantum mechanics and spectroscopy. Topics covered include perturbation theory, two-level systems, light-matter interactions, relaxation in quantum systems, correlation functions and linear response theory, ...

Tokmakoff, Andrei

293

Intrinsic Time Quantum Geometrodynamics  

E-Print Network (OSTI)

Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental canonical commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

Eyo Eyo Ita III; Chopin Soo; Hoi-Lai Yu

2015-01-26T23:59:59.000Z

294

Echo of the Quantum Bounce  

E-Print Network (OSTI)

We identify a signature of quantum gravitational effects that survives from the early universe to the current era: Fluctuations of quantum fields as seen by comoving observers are significantly influenced by the history of the early universe. In particular we show how the existence (or not) of a quantum bounce leaves a trace in the background quantum noise that is not damped and would be non-negligible even nowadays. Furthermore, we estimate an upper bound for the typical energy and length scales where quantum effects are relevant. We discuss how this signature might be observed and therefore used to build falsifiability tests of quantum gravity theories.

Luis J. Garay; Mercedes Martin-Benito; Eduardo Martin-Martinez

2014-02-15T23:59:59.000Z

295

Instantaneous Quantum Computation  

E-Print Network (OSTI)

We examine theoretic architectures and an abstract model for a restricted class of quantum computation, called here instantaneous quantum computation because it allows for essentially no temporal structure within the quantum dynamics. Using the theory of binary matroids, we argue that the paradigm is rich enough to enable sampling from probability distributions that cannot, classically, be sampled from efficiently and accurately. This paradigm also admits simple interactive proof games that may convince a skeptic of the existence of truly quantum effects. Furthermore, these effects can be created using significantly fewer qubits than are required for running Shor's Algorithm.

Dan Shepherd; Michael J. Bremner

2008-09-04T23:59:59.000Z

296

Superluminal neutrino: a quantum weak measurement effect?  

E-Print Network (OSTI)

Superluminal neutrino: a quantum weak measurement effect? Pragya Shukla · Dynamical laws, both in quantum and classical theory, are ?me-symmetric. · Measurements, the result of a measurement performed at a later ?me t1 or previous ?me

297

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

E-Print Network (OSTI)

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

Armiento, Rickard

298

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

E-Print Network (OSTI)

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

Gross, E.K.U.

299

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

E-Print Network (OSTI)

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

Florian, Libisch

300

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

E-Print Network (OSTI)

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

Ramachandran, Bala (Ramu)

Note: This page contains sample records for the topic "theory dft quantum" from the National Library of EnergyBeta (NLEBeta).
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301

Interaction of the cesium cation with calix[4]arene-bis(t-octylbenzo-18-crown-6): Extraction and DFT study  

Science Journals Connector (OSTI)

From extraction experiments and ?-activity measurements, the extraction constant corresponding to the equilibrium Cs+ (aq)+I? (aq)+1 (org)?1?Cs+ (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(1?Cs+,I?)=2.10.1. Further, the stability constant of the 1?Cs+ complex in FS 13 saturated with water was calculated for a temperature of 25C: log?org(1?Cs+)=9.90.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1?Cs+ was derived. In the resulting 1?Cs+ 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? interaction.

Emanuel Makrlk; Petr Toman; Petr Va?ura; Bruce A. Moyer

2013-01-01T23:59:59.000Z

302

Smartphone data safety with quantum cryptography  

NLE Websites -- All DOE Office Websites (Extended Search)

Smartphone data safety with quantum cryptography Smartphone data safety with quantum cryptography Smartphone data safety with quantum cryptography Laws of quantum physics and information theory ensure that smartphones with QKarD could never be compromised. January 20, 2012 The QKarD encodes security keys on a photon using quantum mechanical principles. The miniature transmitter communicates with a trusted authority to generate random cryptographic keys to encode and decode information. The QKarD encodes security keys on a photon using quantum mechanical principles. The laws of quantum physics and information theory ensure that these keys never can be cracked, regardless of advancements in computer technology. New technology brings quantum cryptography to handhelds Laws of quantum physics and information theory ensure that smartphones with

303

Atomistic force field for alumina fit to density functional theory  

SciTech Connect

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

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

2013-11-28T23:59:59.000Z

304

Quantum nonlocality  

SciTech Connect

It is argued that the validity of the predictions of quantum theory in certain spin-correlation experiments entails a violation of Einstein's locality idea that no causal influence can act outside the forward light cone. First, two preliminary arguments suggesting such a violation are reviewed. They both depend, in intermediate stages, on the idea that the results of certain unperformed experiments are physically determinate. The second argument is entangled also with the problem of the meaning of physical reality. A new argument having neither of these characteristics is constructed. It is based strictly on the orthodox ideas of Bohr and Heisenberg, and has no realistic elements, or other ingredients, that are alien to orthodox quantum thinking.

Stapp, H.P.

1988-04-01T23:59:59.000Z

305

Proceedings of Institute of Mathematics of NAS of Ukraine 2004, Vol. 50, Part 3, 14481453 Quantum Phase Space in Relativistic Theory  

E-Print Network (OSTI)

Proceedings of Institute of Mathematics of NAS of Ukraine 2004, Vol. 50, Part 3, 1448­1453 Quantum and C.V. USENKO Institute of Physics of NAS of Ukraine, 46 Nauky Ave., 03028 Kyiv, Ukraine E-mail: sem., 03127 Kyiv, Ukraine E-mail: usenko@phys.univ.kiev.ua Mathematical method of quantum phase space is very

Popovych, Roman

306

Quantum Locality?  

SciTech Connect

Robert Griffiths has recently addressed, within the framework of a consistent quantum theory (CQT) that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues, on the basis of his examination of certain arguments that claim to demonstrate the existence of such nonlocal influences, that such influences do not exist. However, his examination was restricted mainly to hidden-variable-based arguments that include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by attributing to the system properties alien to that system. Hence Griffiths rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his consistent quantum theory shows that the cited proof is valid within that restrictive framework. This necessary existence, within the consistent framework, of long range essentially instantaneous influences refutes the claim made by Griffiths that his consistent framework is superior to the orthodox quantum theory of von Neumann because it does not entail instantaneous influences. An added section responds to Griffiths reply, which cites a litany of ambiguities that seem to restrict, devastatingly, the scope of his CQT formalism, apparently to buttress his claim that my use of that formalism to validate the nonlocality theorem is flawed. But the vagaries that he cites do not upset the proof in question. It is show here in detail why the precise statement of this theorem justifies the specified application of CQT. It is also shown, in response to his challenge, why a putative proof of locality that he has proposed is not valid.

Stapp, Henry

2011-11-10T23:59:59.000Z

307

Semiconductors Used in Photovoltaic and Photocatalytic Devices: Assessing Fundamental Properties from DFT  

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Semiconductors Used in Photovoltaic and Photocatalytic Devices: Assessing Fundamental Properties from DFT ... In a dielectric environment, the electrostatic force between the electron and the hole can be approximated by the eq 1. ... Madelung, O. Semiconductors: Data Handbook, 3rd ed.; Springer: New York, 2004. ...

Tangui Le Bahers; Michel Rrat; Philippe Sautet

2014-02-28T23:59:59.000Z

308

TEDTTC^/Dft Ris-R-641(pN) Methodology forJustification and  

E-Print Network (OSTI)

and optimization of protective mea- sures in case of a reactor accident situation with a large release of fissionTEDTTC^/Dft Risø-R-641(pN) Methodology forJustification and Optimization ofProtective Measures: *»***&*> Methodology forJustification and Optimization of Protective Measures Including a Case Study: Protective

309

A DFT Study of Ethanol Adsorption and Dehydrogenation on Cu/Cr2O3 Catalyst  

Science Journals Connector (OSTI)

In this work, DFT simulation method was used to study the adsorption and dehydrogenation of ethanol on Cu/Cr2O3 catalyst. Firstly, the stable configuration of Cu4 cluster adsorbed on Cr2O3...(001) surface was stu...

Minhua Zhang; Yanping Huang; Ruzhen Li; Guiming Li; Yingzhe Yu

2014-11-01T23:59:59.000Z

310

Coherence in Classical Electromagnetism and Quantum Optics.  

E-Print Network (OSTI)

??This thesis is a study of coherence theory in light in classical electromagnetism and quantum optics. %The coherence is quantified Specifically two quantities are studied: (more)

Mevik, Hanne-Torill

2009-01-01T23:59:59.000Z

311

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

E-Print Network (OSTI)

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

Ceder, Gerbrand

312

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

E-Print Network (OSTI)

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

Herbert, John

313

Hybrid DFT study on the gas-phase SN2 reactions at neutral oxygen  

Science Journals Connector (OSTI)

The hybrid DFT method MPW1K, in conjunction with 6-31+G(d,p) basis sets, has been examined for the gas-phase reactions, Y?+HOX (Y, X=F, Cl, Br, I). Comparison of the results with the high-level G2(+) theory indicates that MPW1K/6-31+G(d,p) approach performs well in describing the potential energy surface for the identity SN2 reactions X?+HOX?HOX+X? (X=Cl, Br, I). The corresponding non-identity reactions (Y?X, Y, X=Cl, Br, I), are exothermic if the nucleophile is the heavier halide, in contrast to the corresponding reactions at carbon. The fluorine behaves different from the other halogens. The reactions Y?+HOF (Y=F, Cl, Br, I) are predicted to form the energetically favorable products YO?+HF with a large driving force(?H=?48.6, ?47.2, ?56.5, ?69.0kJ/mol for Y=F, Cl, Br, I, respectively) and lower reaction enthalpies than the corresponding SN2 reactions by about 60kJ/mol. Central barrier heights (?HYX?) for SN2 reactions in the exothermic directions vary from 52.5kJ/mol for Y=I, X=Br up to 76.6kJ/mol for Y=Br, X=Cl. Overall barriers (?HYXb) for reactions in the exothermic direction are all negative (varying from ?13.8kJ/mol for Y=I, X=Br to ?5.2kJ/mol for Y=Br, X=Cl). Complexation energies (?Hcomp) of the ionmolecule complexes Y??HOX vary from 66.3kJ/mol for Y=I, X=Br to 95.5kJ/mol for Y=Cl, X=Br. The central barrier heights ?HYX? and ?HXY? correlate well with the degree of the O?X and O?Y bond elongation in the transition structures. Both central and overall barriers can be interpreted with the aid of Marcus equation.

Yi Ren; Joel L. Wolk; Shmaryahu Hoz

2003-01-01T23:59:59.000Z

314

"Quantum Field Theory and QCD"  

SciTech Connect

This grant partially funded a meeting, "QFT & QCD: Past, Present and Future" held at Harvard University, Cambridge, MA on March 18-19, 2005. The participants ranged from senior scientists (including at least 9 Nobel Prize winners, and 1 Fields medalist) to graduate students and undergraduates. There were several hundred persons in attendance at each lecture. The lectures ranged from superlative reviews of past progress, lists of important, unsolved questions, to provocative hypotheses for future discovery. The project generated a great deal of interest on the internet, raising awareness and interest in the open questions of theoretical physics.

Jaffe, Arthur M.

2006-02-25T23:59:59.000Z

315

Quantum Privacy and Quantum Coherence  

Science Journals Connector (OSTI)

We derive a simple relation between a quantum channel's capacity to convey coherent (quantum) information and its usefulness for quantum cryptography.

Benjamin Schumacher and Michael D. Westmoreland

1998-06-22T23:59:59.000Z

316

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

E-Print Network (OSTI)

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

Baer, Roi

317

Analytic energy gradients for constrained DFT-configuration interaction  

SciTech Connect

The constrained density functional theory-configuration interaction (CDFT-CI) method has previously been used to calculate ground-state energies and barrier heights, and to describe electronic excited states, in particular conical intersections. However, the method has been limited to evaluating the electronic energy at just a single nuclear configuration, with the gradient of the energy being available only via finite difference. In this paper, we present analytic gradients of the CDFT-CI energy with respect to nuclear coordinates, which gives the potential for accurate geometry optimization and molecular dynamics on both the ground and excited electronic states, a realm which is currently quite challenging for electronic structure theory. We report the performance of CDFT-CI geometry optimization for representative reaction transition states as well as molecules in an excited state. The overall accuracy of CDFT-CI for computing barrier heights is essentially unchanged whether the energies are evaluated at geometries obtained from quadratic configuration-interaction singles and doubles (QCISD) or CDFT-CI, indicating that CDFT-CI produces very good reaction transition states. These results open up tantalizing possibilities for future work on excited states.

Kaduk, Benjamin; Tsuchimochi, Takashi; Van Voorhis, Troy, E-mail: tvan@mit.edu [Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

2014-05-14T23:59:59.000Z

318

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

SciTech Connect

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

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

2014-05-14T23:59:59.000Z

319

Macroscopic quantum tunneling in Josephson junctions -  

E-Print Network (OSTI)

Macroscopic quantum tunneling in Josephson junctions - a method to characterise a well-shielded low Theory 5 1. The classical theory of Josephson junctions . . . . . . . . . . . . . . . . . 9 1-Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2. Josephson junction dynamics . . . . . . . . . . . . . . . . . . . . . . . . 15 2.1 The basics

Gross, Rudolf

320

DFT studies of Indium Nanoclusters (Inn where n=3-10) and Nanotube and their interaction with molecular hydrogen  

E-Print Network (OSTI)

Density functional theory calculations have been performed on Indium nanoclusters (Inn, n= 3 to 10) to explore the relative stability among their different isomers and interaction with H2. Geometry optimizations starting from initial candidate geometries were performed for each cluster size, so as to determine a few low energy isomers for each size. Clusters with planar configuration and high symmetry are found to be more stable. For n=8 there comes transition from 2D to 3D structures, which formed by stacking of planar rings are most stable. Energetically favorable isomers of indium nanoclusters for each size were considered to get H2 adsorbed. In general H2 interaction with these clusters is week but with odd index i.e. 5, 7 and 9 is significant. Indium nanotube also indicates H2 adsorption but Eads increases many folds on introduction of defect in the tube. On basis of these DFT studies we propose indium nanotubes and clusters of particular size appear to be good candidate for hydrogen storage materials.

Baig, Mirza Wasif; Ahmad, Idrees; Siddiq, Muhammad

2014-01-01T23:59:59.000Z

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


321

Tensor rank problem in statistical high-dimensional data and quantum information theory:their comparisons on the methods and the results  

E-Print Network (OSTI)

Quantum communication is concerned with the complexity of entanglement of a state and statistical data analysis is concerned with the complexity of a model. A common key word for both is "rank". In this paper we will show that both community is tracing the same target and that the methods used are slightly different. Two different methods, the range criterion method from quantum communication and the determinant polynomial method, are shown as an examples.

Toshio Sakata; Lin Chen; Toshio Sumi; Mitsuhiro Miyazaki

2009-11-09T23:59:59.000Z

322

Global-to-local incompatibility, monogamy of entanglement, and ground-state dimerization: Theory and observability of quantum frustration in systems with competing interactions  

E-Print Network (OSTI)

Frustration in quantum many body systems is quantified by the degree of incompatibility between the local and global orders associated, respectively, to the ground states of the local interaction terms and the global ground state of the total many-body Hamiltonian. This universal measure is bounded from below by the ground-state bipartite block entanglement. For many-body Hamiltonians that are sums of two-body interaction terms, a further inequality relates quantum frustration to the pairwise entanglement between the constituents of the local interaction terms. This additional bound is a consequence of the limits imposed by monogamy on entanglement shareability. We investigate the behavior of local pair frustration in quantum spin models with competing interactions on different length scales and show that valence bond solids associated to exact ground-state dimerization correspond to a transition from generic frustration, i.e. geometric, common to classical and quantum systems alike, to genuine quantum frustration, i.e. solely due to the non-commutativity of the different local interaction terms. We discuss how such frustration transitions separating genuinely quantum orders from classical-like ones are detected by observable quantities such as the static structure factor and the interferometric visibility.

S. M. Giampaolo; B. C. Hiesmayr; F. Illuminati

2015-01-25T23:59:59.000Z

323

Gain spectra and temperature characteristics of quantum cascade lasers  

Science Journals Connector (OSTI)

We have developed a theory describing the operation of lasers based on intersubband transitions in a quantum well. The theory combines a first-principles description of the intersubband lineshape and the optical gain with kinetic models for carrier heating. ... Keywords: carrier heating, gain spectra, intersubband lineshape, intersubband transitions, kinetic models, laser theory, optical gain, quantum cascade lasers, quantum well, quantum well lasers, room-temperature high-power operation, temperature characteristics

V. Gorfinkel; S. Luryi; B. Gelmont

1995-11-01T23:59:59.000Z

324

Hybrid Quantum Mechanical/Molecular Mechanics Study of the SN2 Reaction of CH3Cl+OH? in Water  

SciTech Connect

The SN2 mechanism for the reaction of CH3Cl + OH? in aqueous solution was investigated using combined quantum mechanical and molecular mechanics methodology. We analyzed structures of reactant, transition and product states along the reaction pathway. The free energy profile was calculated using the multi-layered representation with the DFT and CCSD(T) level of theory for the quantum-mechanical description of the reactive region. Our results show that the aqueous environment has a significant impact on the reaction process. We find that solvation energy contribution raises the reaction barrier by ~18.9 kcal/mol and the reaction free energy by ~24.5 kcal/mol. The presence of the solvent also induces perturbations in the electronic structure of the solute leading to an increase of 3.5 kcal/mol for the reaction barrier and a decrease of 5.6 kcal/mol for the reaction free energy respectively. Combining the results of two previous calculation results on CHCl3 + OH? and CH2Cl2 + OH? reactions in water, we demonstrate that increase in the chlorination of the methyl group (from CH3Cl to CHCl3) is accompanied by the decrease in the free energy reaction barrier, with the CH3Cl + OH? having the largest barrier among the three reactions.

Yin, Hongyun; Wang, Dunyou; Valiev, Marat

2011-11-03T23:59:59.000Z

325

DFT studies of ethylene in femtosecond laser pulses  

E-Print Network (OSTI)

Using time-dependent density functional theory, applied to valence electrons, coupled non-adiabatically to molecular dynamics of the ions, we study the induced dynamics of ethylene subjected to the laser field. We demonstrate the reliable quality of such an approach in comparison to the experimental data on atomic and molecular properties. The impact of ionic motion on the ionization is discussed showing the importance of dealing with electronic and ionic degrees of freedom simultaneously. We explore the various excitation scenarios of ethylene as a function of the laser parameters. We find that the Coulomb fragmentation depends sensitively on the laser frequency. The high laser intensity can cause brute-force Coulomb explosion and the laser pulse length actually has influence on the excitation dynamics of ethylene.

Wang, Z P; Reinhard, P -G; Suraud, E; Zhang, F S

2009-01-01T23:59:59.000Z

326

Types of quantum information  

E-Print Network (OSTI)

Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in quantum terms, of ``classical information.'' Various examples (some updating earlier work) are given of theorems which relate different incompatible kinds of information, and thus have no counterparts in classical information theory.

Robert B. Griffiths

2007-07-25T23:59:59.000Z

327

Types of quantum information  

Science Journals Connector (OSTI)

Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in quantum terms, of classical information. Various examples (some updating earlier work) are given of theorems which relate different incompatible kinds of information, and thus have no counterparts in classical information theory.

Robert B. Griffiths

2007-12-21T23:59:59.000Z

328

Quo Vadis Quantum Mechanics?  

Science Journals Connector (OSTI)

Quantum mechanics is one of the most successful theoretical structures in all of science. Developed between 1925-26 to explain the optical spectrum of atoms, the theory over the succeeding 80 years has been extended, first to quantum field theories, gauge field theories, and now even string theory. It is used every day by thousands of physicists to calculate physical phenomena to exquisite precision, with no ambiguity in the results. To claim that this is a theory which is not understood by those physicists is absurd. And yet, as eminent a physicist as Richard Feynman, who did as much as anyone else to extend quantum theory to field theories and was a master at producing those exquisite calculations, could say that anyone who claimed they understood quantum theory clearly did not understand quantum theory. One hundred years ago Einstein postulated one of the most unsettling features of the theory, the wave-particle duality, with his particulate explanation for light of the photoelectric effect, and an explanation which was in direct conflict with Maxwell's brilliant development of a wave, or field, theory of light. Einstein believed that the particulate nature would ultimately be explainable by some sort of non-linear theory of electromagnetism, and was outraged by the acceptance of the community of the probabilistic quantum theory. His programme was of course dealt a (near?) fatal blow by Bell's discovery that the three desiderata - a theory which agrees with experiment, a theory which is local in its effects, and a theory in which nature, at its heart, is not probabilistic - are incompatible. That discomfort felt by Einstein and by Feynman is felt by numerous other people as well. This discomfort is heightened by the fact that the theory of gravity, another of Einstein's great achievements, has resisted all efforts at reconciliation with quantum mechanics. This book explores that discomfort, and tries to pin down what the locus of that discomfort is. For many, the locus is in the probabilistic nature at the heart of the theory. Nature should surely, at some fundamental level, know what it is doing. The photon, despite our inability to measure it, should know where it is and how fast it is going. The papers by t'Hooft, Hiley, and Smolin fall into this camp. Some suspect that the macroscopic world of our immediate sense experiences, and the microscopic world of quantum phenomena, are genuinely different, that the fundamental conceptual nature of physics changes from one to the other, with some unknown boundary between them. Penrose, in his preface alludes to his speculations on this, as does Leggett to his own speculations in his paper. And a number of articles (e.g., by Hartle, Rovelli, and others) opine that if only everyone looked at quantum mechanics in the right way (their way), it would lose its mystery, and be as natural as Newton's world view. (I myself tend to this position, which is however somewhat tempered by the realization that the clarity and naturalness of my viewpoint is not shared by the others who believe equally firmly in their own natural, clear, but radically different, viewpoint). A number of articles simply examine the counterintuitive nature of quantum theory in general, using it to make sense of time travel (Greenberger and Svozil) and demonstrating the unusual features of induction about the past from present observations within quantum theory (Aharonov and Dolev). The book is not free from rather overblown titles (e.g., 'Liberation and Purification from Classical Prejudice', or 'A Quantum Theory of the Human Person') but those articles nevertheless contain at least amusing speculations. In quantum gravity, the incompatibilities between the two masterstrokes of the twentieth century are highlighted. There is a strong suspicion amongst many in this field that progress in understanding quantum gravity demands a deeper understanding of the great mystery of quantum theory which this book explores. This book is a useful and, at times, fascinating introduction to the flounderings which are taking pla

W G Unruh

2006-01-01T23:59:59.000Z

329

Hydroxide Degradation Pathways for Substituted Trimethylammonium Cations: A DFT Study  

SciTech Connect

Substituted trimethylammonium cations serve as small molecule analogues for tetherable cations in anion exchange membranes. In turn, these membranes serve as the basis for alkaline membrane fuel cells by allowing facile conduction of hydroxide. As these cations are susceptible to hydroxide attack, they degrade over time and greatly limit the lifetime of the fuel cell. In this research, we performed density functional theory calculations to investigate the degradation pathways of substituted trimethylammonium cations to probe the relative durability of cation tethering strategies in alkyl and aromatic tethers. Our results show that significant changes in calculated energy barriers occur when substitution groups change. Specifically, we have found that, when available, the Hofmann elimination pathway is the most vulnerable pathway for degradation; however, this barrier is also found to depend on the carbon chain length and number of hydrogens susceptible to Hofmann elimination. S{sub N}2 barriers were also investigated for both methyl groups and substitution groups. The reported findings give important insight into potential tethering strategies for trimethylammonium cations in anion exchange membranes.

Long, H.; Kim, K.; Pivovar, B. S.

2012-05-03T23:59:59.000Z

330

Quantum ferroelectrics of mixed crystals  

Science Journals Connector (OSTI)

The inverse dielectric susceptibility for quantum ferroelectrics in mixed crystals is computed. As in the perfect crystals we find a logarithmic correction to the quantum mean-field theory. For mixed crystals the correction increases faster in the vicinity of the critical point.

D. Schmeltzer

1984-03-01T23:59:59.000Z

331

Quantum recoil and Bohm diffusion  

SciTech Connect

It is argued that the inclusion of the Bohm potential in quantum fluid equations is equivalent to inclusion of a nonrelativistic form of the quantum recoil in plasma kinetic theory. The Bohm term is incorrect when applied to waves with phase speed greater than the speed of light.

Melrose, D. B.; Mushtaq, A. [School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia)

2009-09-15T23:59:59.000Z

332

Strong reactions in quantum super PDEs. III: Exotic quantum supergravity  

E-Print Network (OSTI)

Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.

Agostino Prstaro

2015-02-01T23:59:59.000Z

333

Layered Tantalum Oxynitride Nanorod Array Carpets for Efficient Photoelectrochemical Conversion of Solar Energy: Experimental and DFT Insights  

Science Journals Connector (OSTI)

Layered Tantalum Oxynitride Nanorod Array Carpets for Efficient Photoelectrochemical Conversion of Solar Energy: Experimental and DFT Insights ... This difference in bond energy resulted in narrower band gap energies in oxynitrides compared to their metal oxide counterparts. ...

Nageh K. Allam; Basamat S. Shaheen; Ahmed M. Hafez

2014-03-25T23:59:59.000Z

334

How do vibrations change their composition upon electronic excitation? EXSY-T2D-IR measurements challenge DFT calculations.  

Science Journals Connector (OSTI)

The composition of excited state vibrations can be disentangled by projecting ground state vibrations on them using exchange transient two-dimensional IR spectroscopy. The results challenge excited state DFT c...

Andreas Messmer; Ana-Maria Blanco Rodrguez; Jakub ebera

2009-01-01T23:59:59.000Z

335

Molecular Binding in Post-KohnSham Orbital-Free DFT  

Science Journals Connector (OSTI)

Alex Borgoo *, James A. Green , and David J. Tozer * ... Molecular binding in post-KohnSham orbital-free DFT is investigated, using noninteracting kinetic energy functionals that satisfy the uniform electron gas condition and which are inhomogeneous under density scaling. ... A parameter is introduced that quantifies binding, and a series of functionals are determined from fits to near-exact effective homogeneities and/or KohnSham noninteracting kinetic energies. ...

Alex Borgoo; James A. Green; David J. Tozer

2014-10-30T23:59:59.000Z

336

Combined Investigation of Water Sorption on TiO2 Rutile (110) Single Crystal Face: XPS vs. Periodic DFT  

E-Print Network (OSTI)

1 Combined Investigation of Water Sorption on TiO2 Rutile (110) Single Crystal Face: XPS vs(0)169157150; e-mail: roques@ipno.in2p3.fr Keywords: water, sorption, rutile TiO2, (110), XPS, DFT. Abstract XPS and periodic DFT calculations have been used to investigate water sorption on the TiO2 rutile (110) face. Two

Paris-Sud XI, Université de

337

Quantum Error Correction Beyond Completely Positive Maps  

E-Print Network (OSTI)

By introducing an operator sum representation for arbitrary linear maps, we develop a generalized theory of quantum error correction (QEC) that applies to any linear map, in particular maps that are not completely positive (CP). This theory of "linear quantum error correction" is applicable in cases where the standard and restrictive assumption of a factorized initial system-bath state does not apply.

A. Shabani; D. A. Lidar

2009-10-21T23:59:59.000Z

338

Synthesis of linear quantum stochastic systems via quantum feedback networks  

E-Print Network (OSTI)

Recent theoretical and experimental investigations of coherent feedback control, the feedback control of a quantum system with another quantum system, has raised the important problem of how to synthesize a class of quantum systems, called the class of linear quantum stochastic systems, from basic quantum optical components and devices in a systematic way. The synthesis theory sought in this case can be naturally viewed as a quantum analogue of linear electrical network synthesis theory and as such has potential for applications beyond the realization of coherent feedback controllers. In earlier work, Nurdin, James and Doherty have established that an arbitrary linear quantum stochastic system can be realized as a cascade connection of simpler one degree of freedom quantum harmonic oscillators, together with a direct interaction Hamiltonian which is bilinear in the canonical operators of the oscillators. However, from an experimental perspective and based on current methods and technologies, direct interaction Hamiltonians are challenging to implement for systems with more than just a few degrees of freedom. In order to facilitate more tractable physical realizations of these systems, this paper develops a new synthesis algorithm for linear quantum stochastic systems that relies solely on field-mediated interactions, including in implementation of the direct interaction Hamiltonian. Explicit synthesis examples are provided to illustrate the realization of two degrees of freedom linear quantum stochastic systems using the new algorithm.

H. I. Nurdin

2009-05-06T23:59:59.000Z

339

Quantum correlation via quantum coherence  

E-Print Network (OSTI)

Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes of quantum coherence. We propose a revised measure for total coherence and find that this measure can lead to a symmetric version of geometric quantum correlation which is analytic for two qubits. In particular, this measure can also arrive at a monogamy equality on the distribution of quantum coherence. Finally, we also quantify a remaining type of quantum coherence and find that for two qubits it is directly connected with quantum nonlocality.

Chang-shui Yu; Yang Zhang; Haiqing Zhao

2014-02-19T23:59:59.000Z

340

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

E-Print Network (OSTI)

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

Chu, Shih-I

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


341

Optimal control in an open quantum system : selecting DNP pathways in an electron-nuclear system  

E-Print Network (OSTI)

There is much interest in improving quantum control techniques for the purposes of quantum information processing. High fidelity control is necessary for the future of quantum computing. Optimal control theory has been ...

Sheldon, Sarah (Sarah Elizabeth)

2013-01-01T23:59:59.000Z

342

Loop Quantum Gravity 1. Classical framework : Ashtekar-Barbero connection  

E-Print Network (OSTI)

gravity Why Quantum Gravity ? Gravitation vs. Quantum Physics : the two infinities Gravitation : large Quantum Gravity ? Gravitation vs. Quantum Physics : the two infinities Gravitation : large scales-perturbative renormalization Gravity is not a fundamental theory but it is effective (law energy) · it has to be modified

Sart, Remi

343

Chiral Quantum Walks  

E-Print Network (OSTI)

Wigner separated the possible types of symmetries in quantum theory into those symmetries that are unitary and those that are antiunitary. Unitary symmetries have been well studied whereas antiunitary symmetries and the physical implications associated with time-reversal symmetry breaking have had little influence on quantum information science. Here we develop a quantum circuits version of time-reversal symmetry theory, classifying time-symmetric and time-asymmetric Hamiltonians and circuits in terms of their underlying network elements and geometric structures. These results reveal that many of the typical quantum circuit networks found across the field of quantum information science exhibit time-asymmetry. We then experimentally implement the most fundamental time-reversal asymmetric process, applying local gates in an otherwise time-symmetric circuit to induce time-reversal asymmetry and thereby achieve (i) directional biasing in the transition probability between basis states, (ii) the enhancement of and (iii) the suppression of these transport probabilities. Our results imply that the physical effect of time-symmetry breaking plays an essential role in coherent transport and its control represents an omnipresent yet essentially untapped resource in quantum transport science.

DaWei Lu; Jacob D. Biamonte; Jun Li; Hang Li; Tomi H. Johnson; Ville Bergholm; Mauro Faccin; Zoltn Zimbors; Raymond Laflamme; Jonathan Baugh; Seth Lloyd

2014-05-23T23:59:59.000Z

344

Quantum decoherence of the damped harmonic oscillator  

E-Print Network (OSTI)

In the framework of the Lindblad theory for open quantum systems, we determine the degree of quantum decoherence of a harmonic oscillator interacting with a thermal bath. It is found that the system manifests a quantum decoherence which is more and more significant in time. We also calculate the decoherence time and show that it has the same scale as the time after which thermal fluctuations become comparable with quantum fluctuations.

A. Isar

2006-06-27T23:59:59.000Z

345

Phenomenological Quantum Gravity  

E-Print Network (OSTI)

Planck scale physics represents a future challenge, located between particle physics and general relativity. The Planck scale marks a threshold beyond which the old description of spacetime breaks down and conceptually new phenomena must appear. In the last years, increased efforts have been made to examine the phenomenology of quantum gravity, even if the full theory is still unknown.

S. Hossenfelder

2006-11-01T23:59:59.000Z

346

Resummed Quantum Gravity  

E-Print Network (OSTI)

We present the current status of the a new approach to quantum general relativity based on the exact resummation of its perturbative series as that series was formulated by Feynman. We show that the resummed theory is UV finite and we present some phenomenological applications as well.

B. F. L. Ward

2006-10-18T23:59:59.000Z

347

Quantum cosmology: a review  

E-Print Network (OSTI)

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.

Bojowald, Martin

2015-01-01T23:59:59.000Z

348

Sequential decoupling of negative-energy states in Douglas-Kroll-Hess theory  

E-Print Network (OSTI)

Here, we review the historical development, current status, and prospects of Douglas--Kroll--Hess theory as a quantum chemical relativistic electrons-only theory.

Reiher, Markus

2015-01-01T23:59:59.000Z

349

Quantum Optical State Comparison Amplifier  

E-Print Network (OSTI)

It is a fundamental principle of quantum theory that an unknown state cannot be copied or, as a consequence, an unknown optical signal cannot be amplified deterministically and perfectly. Here we describe a protocol that provides nondeterministic quantum optical amplification in the coherent state basis with high gain, high fidelity and which does not use quantum resources. The scheme is based on two mature quantum optical technologies, coherent state comparison and photon subtraction. The method compares favourably with all previous nondeterministic amplifiers in terms of fidelity and success probability.

Electra Eleftheriadou; Stephen M. Barnett; John Jeffers

2013-11-22T23:59:59.000Z

350

Supersymmetric gauge theories, quantisation of moduli spaces of flat connections, and Liouville theory  

E-Print Network (OSTI)

This is the 11th article in the collection of reviews "Exact results in N=2 supersymmetric gauge theories", ed. J. Teschner. It describes an approach to understanding the 4d/2d relations discovered by Alday, Gaiotto and Tachikawa by establishing a triangle of relations between the zero mode quantum mechanics obtained by localisation of class $\\cal S$ theories, the quantum theory obtained by quantisation of Hitchin moduli spaces, and conformal field theory.

Jrg Teschner

2014-12-22T23:59:59.000Z

351

Supersymmetric gauge theories, quantisation of moduli spaces of flat connections, and Liouville theory  

E-Print Network (OSTI)

This is the 11th article in the collection of reviews "Exact results in N=2 supersymmetric gauge theories", ed. J. Teschner. It describes an approach to understanding the 4d/2d relations discovered by Alday, Gaiotto and Tachikawa by establishing a triangle of relations between the zero mode quantum mechanics obtained by localisation of class $\\cal S$ theories, the quantum theory obtained by quantisation of Hitchin moduli spaces, and conformal field theory.

Teschner, Jrg

2014-01-01T23:59:59.000Z

352

IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS--PART A: SYSTEMS AND HUMANS, VOL. 36, NO. 5, SEPTEMBER 2006 943 Extending the Decision Field Theory to Model  

E-Print Network (OSTI)

, SEPTEMBER 2006 943 Extending the Decision Field Theory to Model Operators' Reliance on Automation by describing a quantitative model of trust in automation. We extend decision field theory (DFT) to describe the multiple sequential decisions that characterize reliance on au- tomation in supervisory control situations

Lee, John D.

353

Geodesic multiplication as a tool for classical and quantum gravity  

E-Print Network (OSTI)

Algebraic systems called the local geodesic loops and their tangent Akivis algebras are considered. Their possible role in theory of gravity is considered. Quantum conditions for the infinitesimal quantum events are proposed.

Piret Kuusk; Eugen Paal

2008-03-08T23:59:59.000Z

354

Quantum Institute  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum Institute Quantum Institute Quantum Institute A new research frontier awaits! Our door is open and we thrive on mutually beneficial partnerships, collaborations that drive innovations and new technologies. Contact Leader Malcolm Boshier (505) 665-8892 Email Two of LANL's most successful quantum technology initiatives: quantum cryptography and the race for quantum computer The area of quantum information, science, and technology is rapidly evolving, with important applications in the areas of quantum cryptography, quantum computing, quantum metrology, and advanced quantum-based sensors, some of which are directly relevant to the Laboratory's national security mission. Mission Foster a vigorous intellectual environment at LANL Define and develop strategic thrusts Target and pursue funding opportunities

355

Quantum discord  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum discord Quantum discord 1663 Los Alamos science and technology magazine Latest Issue:November 2013 All Issues » submit Quantum discord A distinguishing aspect of quantum mechanics discovered at Los Alamos that may be critical to building a quantum computer March 25, 2013 Spinning coins turning into binary numbers Quantum computing Quantum computing can be carried out without the delicate entanglement of qubits previously believed to be necessary Quantum computing, in which quantum bits of information (or qubits) juggle a "superposition" of multiple values simultaneously, offers to unleash tremendous computational power if the qubits can be effectively isolated to prevent decoherence: information describing quantum states dispersing into the environment. But recent research has shown that quantum computing can be carried out

356

Quantum Simulation  

E-Print Network (OSTI)

Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry and cosmology. Quantum simulation could be implemented using quantum computers, but also with simpler, analog devices that would require less control, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar molecules, electrons in semiconductors, superconducting circuits, nuclear spins and photons have been proposed as quantum simulators. This review outlines the main theoretical and experimental aspects of quantum simulation and emphasizes some of the challenges and promises of this fast-growing field.

I. M. Georgescu; S. Ashhab; Franco Nori

2014-03-13T23:59:59.000Z

357

Subsystem real-time Time Dependent Density Functional Theory  

E-Print Network (OSTI)

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

Krishtal, Alisa; Pavanello, Michele

2015-01-01T23:59:59.000Z

358

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

E-Print Network (OSTI)

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

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

2015-01-01T23:59:59.000Z

359

Quantum Non-Objectivity from Performativity of Quantum Phenomena  

E-Print Network (OSTI)

We analyze the logical foundations of quantum mechanics (QM) by stressing non-objectivity of quantum observables which is a consequence of the absence of logical atoms in QM. We argue that the matter of quantum non-objectivity is that, on the one hand, the formalism of QM constructed as a mathematical theory is self-consistent, but, on the other hand, quantum phenomena as results of experimenter's performances are not self-consistent. This self-inconsistency is an effect of that the language of QM differs much from the language of human performances. The first is the language of a mathematical theory which uses some Aristotelian and Russellian assumptions (e.g., the assumption that there are logical atoms). The second language consists of performative propositions which are self-inconsistent only from the viewpoint of conventional mathematical theory, but they satisfy another logic which is non-Aristotelian. Hence, the representation of quantum reality in linguistic terms may be different: from a mathematical theory to a logic of performative propositions. To solve quantum self-inconsistency, we apply the formalism of non-classical self-referent logics.

Andrei Khrennikov; Andrew Schumann

2014-04-04T23:59:59.000Z

360

Determination of the binding energies of the np Rydberg states of H{sub 2}, HD, and D{sub 2} from high-resolution spectroscopic data by multichannel quantum-defect theory  

SciTech Connect

Multichannel quantum-defect theory (MQDT) is used to calculate the electron binding energies of np Rydberg states of H{sub 2}, HD, and D{sub 2} around n = 60 at an accuracy of better than 0.5?MHz. The theory includes the effects of rovibronic channel interactions and the hyperfine structure, and has been extended to the calculation of the asymmetric hyperfine structure of Rydberg states of a heteronuclear diatomic molecule (HD). Starting values for the eigenquantum-defect parameters of MQDT were extracted from ab initio potential-energy functions for the low-lying p Rydberg states of molecular hydrogen and subsequently refined in a global weighted fit to available experimental data on the singlet and triplet Rydberg states of H{sub 2} and D{sub 2}. The electron binding energies of high-np Rydberg states derived in this work represent important quantities for future determinations of the adiabatic ionization energies of H{sub 2}, HD, and D{sub 2} at sub-MHz accuracy.

Sprecher, Daniel; Merkt, Frdric, E-mail: frederic.merkt@phys.chem.ethz.ch [Laboratorium fr Physikalische Chemie, ETH-Zrich, 8093 Zrich (Switzerland)] [Laboratorium fr Physikalische Chemie, ETH-Zrich, 8093 Zrich (Switzerland); Jungen, Christian [Laboratoire Aim Cotton du CNRS, Universit de Paris-Sud, 91405 Orsay (France)] [Laboratoire Aim Cotton du CNRS, Universit de Paris-Sud, 91405 Orsay (France)

2014-03-14T23:59:59.000Z

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


361

Quantum Machines  

E-Print Network (OSTI)

We discuss quantum information processing machines. We start with single purpose machines that either redistribute quantum information or identify quantum states. We then move on to machines that can perform a number of functions, with the function they perform being determined by a program, which is itself a quantum state. Examples of both deterministic and probabilistic programmable machines are given, and we conclude with a discussion of the utility of quantum programs.

Mark Hillery; Vladimir Buzek

2009-03-24T23:59:59.000Z

362

Physics as quantum information processing  

E-Print Network (OSTI)

The experience from Quantum Information has lead us to look at Quantum Theory (QT) and the whole Physics from a different angle. The information-theoretical paradigm---"It from Bit'---prophesied by John Archibald Wheeler is relentlessly advancing. Recently it has been shown that QT is derivable from pure informational principles. The possibility that there is only QT at the foundations of Physics has been then considered, with space-time, Relativity, quantization rules and Quantum Field Theory (QFT) emerging from a quantum-information processing. The resulting theory is a discrete version of QFT with automatic relativistic invariance, and without fields, Hamiltonian, and quantization rules. In this paper I review some recent advances on these lines. In particular: i) How space-time and relativistic covariance emerge from the quantum computation; ii) The derivation of the Dirac equation as free information flow, without imposing Lorentz covariance; iii) the information-theoretical meaning of inertial mass and Planck constant; iv) An observable consequence of the theory: a mass-dependent refraction index of vacuum. I will then conclude with two possible routes to Quantum Gravity.

Giacomo Mauro D'Ariano

2010-12-12T23:59:59.000Z

363

Estimation of expected human attention weights based on a decision field theory model  

Science Journals Connector (OSTI)

Abstract Modeling human decision making behavior is of great interest in understanding how a decision maker weights different decision attributes when making a decision. Such knowledge is critically important in helping predict future decisions, evaluating human decision performance, and improving the design of human and machine interface systems. Decision field theory (DFT) provides a psychological representation of the cognitive deliberation process, which is driven by the fluctuations of a persons attention among decision attributes. In this research area, the most common use of a DFT model is to estimate or predict the human decisions by using a set of pre-specified expected attention weights (EAWs) in the DFT model. Unlike other research, this paper extends the capabilities of DFT in a complementary direction, showing how to fit or train a DFT model by estimating the EAW based on sequentially obtained samples of decision trials. Furthermore, the inherent connection between the EAW and the decision choice uncertainty is investigated. The proposed modeling method is discussed in detail for a two-alternative decision scenario based on two attributes. Both simulations and a case study are conducted in the paper to demonstrate the effectiveness of the proposed modeling approach.

Andres G. Abad; Jionghua (Judy) Jin; Young-Jun Son

2014-01-01T23:59:59.000Z

364

Divergences of generalized quantum electrodynamics on the Lorenz gauge  

SciTech Connect

In this paper we study the Generalized Quantum Electrodynamics (GQED4) on the Lorenz gauge condition and show that divergences are still present in the theory.

Bufalo, R.; Pimentel, B. M. [Instituto de Fisica Teorica, UNESP - Sao Paulo State University P. O. Box 70532-2, 01156-970, Sao Paulo, SP (Brazil); Zambrano, G. E. [Departamento de Fisica, Universidad de Narino Calle 18 Carrera 50, San Juan de Pasto, Narino (Colombia)

2013-03-25T23:59:59.000Z

365

Dynamic modeling and optimal control of DFIG wind energy systems using DFT and NSGA-II  

Science Journals Connector (OSTI)

Abstract Once a doubly-fed induction generator (DFIG) is subjected to a disturbance by a change in the wind speed, the stator flux cannot change instantly. Under this condition, rotor back-EMF voltages reflect the effects of stator dynamics on rotor current dynamics, and have an important role on the oscillations of the rotor current. These oscillations decrease the DFIG system reliability and gear lifetime. Moreover, by focusing only on small signal analysis, the dynamic damping performance immediately following such disturbances is often degraded. Additional improvement in performance will be achieved if discrete Fourier transform (DFT) is used to quantify damping characteristic of the rotor current during changes of the operating points. This paper introduces an optimization technique based on non-dominated sorting genetic algorithm-II (NSGA-II) incorporating DFT analysis to achieve better control performance for DFIG system stability. Considering small signal stability, the main purpose of the control system in the present paper is to increase the system damping ratio as well as to guarantee enough stability margin. Eigenvalue analysis and time-domain simulations have been presented to demonstrate that the proposed optimizing method yields better control performance in comparison with one designed using mere eigenvalue relocation.

M. Zamanifar; B. Fani; M.E.H. Golshan; H.R. Karshenas

2014-01-01T23:59:59.000Z

366

Information and quantum nonseparability  

Science Journals Connector (OSTI)

An information-theoretic inequality analogous to the well-known result of Bell [Physics 1, 195 (1964)] is formulated using the concept of information distance. This inequality, like Bells, is true for all local-hidden-variable theories, but not for quantum mechanics. The metric space structure of this new inequality suggests a reformulation of familiar Bell inequalities in terms of a covariance distance. Quantum nonseparability can be demonstrated through violations of these inequalities even in cases where the correlation between two systems is extremely weak. The connection between nonseparability and complementarity is also briefly discussed in this paper.

B. W. Schumacher

1991-12-01T23:59:59.000Z

367

Fields and Quantum Mechanics  

E-Print Network (OSTI)

The quantum field theories (QFT) constructed in [1,2] include phenomenology of interest. The constructions approximate: scattering by $1/r$ and Yukawa potentials in non-relativistic approximations; and the first contributing order of the Feynman series for Compton scattering. To have a semi-norm, photon states are constrained to transverse polarizations and for Compton scattering, the constructed cross section deviates at large momentum exchanges from the cross section prediction of the Feynman rules. Discussion includes the incompatibility of canonical quantization with the constructed interacting fields, and the role of interpretations of quantum mechanics in realizing QFT.

Glenn Eric Johnson

2014-12-21T23:59:59.000Z

368

Localized Orbital Corrections for the Barrier Heights in Density Functional Theory  

Science Journals Connector (OSTI)

In these cases, we have had to make decisions concerning which data to employ, and the choices are described below. ... Therefore, we must decide upon one resonance structure for each in order to successfully apply the LOC scheme. ... From an assessment of G2 and d. functional theories (DFT) on this test set G2 theory is the most reliable method both in terms of av. ...

Michelle Lynn Hall; Dahlia A. Goldfeld; Arteum D. Bochevarov; Richard A. Friesner

2009-10-27T23:59:59.000Z

369

Theory and Modeling of Weakly Bound/Physisorbed Materials for Hydrogen Storage  

NLE Websites -- All DOE Office Websites (Extended Search)

and Modeling of and Modeling of Weakly Bound/Physisorbed Materials for Hydrogen Storage Andrew Williamson Quantum Simulations Group Lawrence Livermore National Laboratory Tadashi Ogitsu Lawrence Livermore National Laboratory Yong-Hyun Kim, Mike Heben, and Shengbai Zhang National Renewable Energy Laboratory UCRL-209054 This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. Outline * Storage by physisorption: - CNT, fullerenes, carbon aerogels - Doping, Decorating, Charging * Accuracy of Methods: DFT, QMC and Quantum Chemistry - Van der Waals interactions - * Use of DFT to screen for new compounds - 2 binding to doped fullerenes * LDA, GGA and ad-hoc corrections to pseudopotentials

370

Turbocharging Quantum Tomography.  

SciTech Connect

Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography su %7C ers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. We describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more e %7C ectively detect and characterize quantum noise using carefully tailored ensembles of input states.

Blume-Kohout, Robin J; Gamble, John King,; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael

2015-01-01T23:59:59.000Z

371

Theory and fabrication of evanescently-coupled photoluminescent devices  

E-Print Network (OSTI)

This thesis discusses the theory and implementation of evanescently-coupled photoluminescent devices. We demonstrate the feasibility of efficient, spectrally tunable lighting devices through quantum dot photoluminescence. ...

Friend, David Harry

2008-01-01T23:59:59.000Z

372

Modern applications of covariant density functional theory  

E-Print Network (OSTI)

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

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

2011-09-19T23:59:59.000Z

373

Randomization theorems for quantum channels  

E-Print Network (OSTI)

The classical randomization criterion is an important result of statistical decision theory. Recently, a quantum analogue has been proposed, giving equivalent conditions for two sets of quantum states, ensuring existence of a quantum channel mapping one set close to the other, in $L_1$-distance. In the present paper, we extend these concepts in several ways. First, sets of states are replaced by channels and randomization is performed by either post- or pre-composition with another channel. The $L_1$-distance is replaced by the diamond norm. Secondly, the maps are not required to be completely positive, but positivity is given by an admissible family of convex cones. It is shown that the randomization theorems, generalizing both quantum and classical randomization criteria, can be proved in the framework of base section norms, including the diamond norm and its dual. The theory of such norms is developed in the Appendix.

Anna Jencova

2014-04-15T23:59:59.000Z

374

Quantum Espresso/PWscf at NERSC  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum ESPRESSO/PWscf Quantum ESPRESSO/PWscf Quantum ESPRESSO/PWscf Description Quantum ESPRESSO is an integrated suite of computer codes for electronic structure calculations and materials modeling at the nanoscale. It builds on the electronic structure codes PWscf, PHONON, CP90, FPMD, and Wannier. It is based on density-functional theory, plane waves, and pseudopotentials (both norm-conserving and ultrasoft). How to Access Quantum ESPRESSO NERSC uses modules to manage access to software. To use the default version of Espresso, type: % module load espresso Using Quantum ESPRESSO on a Cray System There are two ways of running Quantum ESPRESSO on a Cray system: submitting a batch job, or running interactively in an interactive batch session. Sample batch script to run Quantum ESPRESSO on Hopper:

375

Derivation of quantum probabilities from deterministic evolution  

E-Print Network (OSTI)

The predictions of quantum mechanics are probabilistic. Quantum probabilities are extracted using a postulate of the theory called the Born rule, the status of which is central to the "measurement problem" of quantum mechanics. Efforts to justify the Born rule from other physical principles, and thus elucidate the measurement process, have involved lengthy statistical or information-theoretic arguments. Here we show that Bohm's deterministic formulation of quantum mechanics allows the Born rule for measurements on a single system to be derived, without any statistical assumptions. We solve a simple example where the creation of an ensemble of identical quantum states, together with position measurements on those states, are described by Bohm's quantum dynamics. The calculated measurement outcomes agree with the Born-rule probabilities, which are thus a consequence of deterministic evolution. Our results demonstrate that quantum probabilities can emerge from simple dynamical laws alone, and they support the view that there is no underlying indeterminism in quantum phenomena.

T. G. Philbin

2014-10-15T23:59:59.000Z

376

Quantum Chemical Simulations Reveal Acetylene-Based Growth Mechanisms in the Chemical Vapor Deposition Synthesis of Carbon Nanotubes  

SciTech Connect

Nonequilibrium quantum chemical molecular dynamics (QM/MD) simulation of early stages in the nucleation process of carbon nanotubes from acetylene feedstock on an Fe38 cluster was performed based on the density-functional tight-binding (DFTB) potential. Representative chemical reactions were studied by complimentary static DFTB and density functional theory (DFT) calculations. Oligomerization and cross-linking reactions between carbon chains were found as the main reaction pathways similar to that suggested in previous experimental work. The calculations highlight the inhibiting effect of hydrogen for the condensation of carbon ring networks, and a propensity for hydrogen disproportionation, thus enriching the hydrogen content in already hydrogen-rich species and abstracting hydrogen content in already hydrogen-deficient clusters. The ethynyl radical C2H was found as a reactive, yet continually regenerated species, facilitating hydrogen transfer reactions across the hydrocarbon clusters. The nonequilibrium QM/MD simulations show the prevalence of a pentagon-first nucleation mechanism where hydrogen may take the role of one arm of an sp2 carbon Y-junction. The results challenge the importance of the metal carbide formation for SWCNT cap nucleation in the VLS model and suggest possible alternative routes following hydrogen-abstraction acetylene addition (HACA)-like mechanisms commonly discussed in combustion synthesis.

Eres, Gyula [ORNL] [ORNL; Wang, Ying [Nagoya University, Japan] [Nagoya University, Japan; Gao, Xingfa [Institute of High Energy Physics, Chinese Academy of Sciences, China] [Institute of High Energy Physics, Chinese Academy of Sciences, China; Qian, Hu-Jun [Jilin University, Changchun] [Jilin University, Changchun; Ohta, Yasuhito [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan] [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan; Wu, Xiaona [Nagoya University, Japan] [Nagoya University, Japan; Morokuma, Keiji [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan] [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan; Irle, Stephan [WPI-Institute of Transformative Bio-Molecules and Department of Chemistry, Nagoya University, Japan] [WPI-Institute of Transformative Bio-Molecules and Department of Chemistry, Nagoya University, Japan

2014-01-01T23:59:59.000Z

377

On the 'principle of the quantumness', the quantumness of Relativity, and the computational grand-unification  

SciTech Connect

I will argue that the proposal of establishing operational foundations of Quantum Theory should have top-priority, and that the Lucien Hardy's program on Quantum Gravity should be paralleled by an analogous program on Quantum Field Theory (QFT), which needs to be reformulated, notwithstanding its experimental success. In this paper, after reviewing recently suggested operational 'principles of the quantumness', I address the problem on whether Quantum Theory and Special Relativity are unrelated theories, or instead, if the one implies the other. I show how Special Relativity can be indeed derived from causality of Quantum Theory, within the computational paradigm 'the universe is a huge quantum computer', reformulating QFT as a Quantum-Computational Field Theory (QCFT). In QCFT Special Relativity emerges from the fabric of the computational network, which also naturally embeds gauge invariance. In this scheme even the quantization rule and the Planck constant can in principle be derived as emergent from the underlying causal tapestry of space-time. In this way Quantum Theory remains the only theory operating the huge computer of the universe.Is the computational paradigm only a speculative tautology (theory as simulation of reality), or does it have a scientific value? The answer will come from Occam's razor, depending on the mathematical simplicity of QCFT. Here I will just start scratching the surface of QCFT, analyzing simple field theories, including Dirac's. The number of problems and unmotivated recipes that plague QFT strongly motivates us to undertake the QCFT project, since QCFT makes all such problems manifest, and forces a re-foundation of QFT.

D'Ariano, Giacomo Mauro [QUIT Group, Dipartimento di Fisica 'A. Volta', 27100 Pavia (Italy) and Center for Photonic Communication and Computing, Northwestern University, Evanston, IL 60208 (Italy)

2010-05-04T23:59:59.000Z

378

Quantum measurements of coupled systems  

SciTech Connect

We propose an approach to measuring coupled systems, which gives a parametrically smaller error than the conventional fast projective measurements. The measurement error is due to the excitations being not entirely localized on individual systems even where the excitation energies are different. Our approach combines spectral selectivity of the detector with temporal resolution and uses the ideas of the quantum diffusion theory. The results bear on quantum computing with perpetually coupled qubits.

Fedichkin, L.; Dykman, M. I. [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Shapiro, M. [Department of Mathematics, Michigan State University, East Lansing, Michigan 48824 (United States)

2009-07-15T23:59:59.000Z

379

8.251 String Theory for Undergraduates, Spring 2005  

E-Print Network (OSTI)

Introduction to the main concepts of string theory to undergraduates. Since string theory is quantum mechanics of a relativistic string, the foundations of the subject can be explained to students exposed to both special ...

Zwiebach, Barton

380

I, Quantum Robot: Quantum Mind control on a Quantum Computer  

E-Print Network (OSTI)

The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be the use of coherent states in brain signals.

Paola Zizzi

2008-12-25T23:59:59.000Z

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


381

The DFT+Umol method and its application to the adsorption of CO on platinum model clusters  

SciTech Connect

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.

Soini, Thomas M.; Krger, Sven [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany)] [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany); Rsch, Notker, E-mail: roesch@mytum.de [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany) [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 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

382

Exploring the interaction between lithium ion and defective graphene surface using dispersion corrected DFT studies  

SciTech Connect

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.

Vijayakumar, M.; Hu, Jian Z.

2013-10-15T23:59:59.000Z

383

An Efficient Arithmetic Sum-of-Product (SOP) based Multiplication Approach for FIR Filters and DFT  

E-Print Network (OSTI)

, the output of a FIR filter is the weighted sum of the current value and a finite number of previous values of the input. An important property of FIR filters is their inherent stability due to the lack of feedback from the output. Y (n) = N?1 ? l=0 x(n... . . . . . . +++ . . . . . .+ + + + MCM z?1 z?1 z?1 z?1 a) Direct Form Realization z?1 z?1 z?1 z?1 b) Transposed Direct Form Realization c0 c1 c2 c3 cN?1 cN?3cN?1 c0cN?2 x(n) x(n) SOP Y (n) Y (n) cN?4 Fig. I.1. Implementation of DFT The previous approaches for solving...

Kumar, Rajeev

2013-04-24T23:59:59.000Z

384

Effective field theory for dilute fermions with pairing  

SciTech Connect

Effective field theory (EFT) methods for a uniform system of fermions with short-range, natural interactions are extended to include pairing correlations, as part of a program to develop a systematic Kohn-Sham density functional theory (DFT) for medium and heavy nuclei. An effective action formalism for local composite operators leads to a free-energy functional that includes pairing by applying an inversion method order by order in the EFT expansion. A consistent renormalization scheme is demonstrated for the uniform system through next-to-leading order, which includes induced-interaction corrections to pairing.

Furnstahl, R.J. [Department of Physics, Ohio State University, Columbus, OH 43210 (United States)], E-mail: furnstahl.1@osu.edu; Hammer, H.-W. [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, Nussallee 14-16, D-53115 Bonn (Germany)], E-mail: hammer@itkp.uni-bonn.de; Puglia, S.J. [SBIG PLC, Berkeley Square House, London W1J 6BR (United Kingdom)], E-mail: spuglia@sbiguk.com

2007-11-15T23:59:59.000Z

385

Entanglement Cost of Quantum Channels  

E-Print Network (OSTI)

The entanglement cost of a quantum channel is the minimal rate at which entanglement (between sender and receiver) is needed in order to simulate many copies of a quantum channel in the presence of free classical communication. In this paper we show how to express this quantity as a regularized optimization of the entanglement formation over states that can be generated between sender and receiver. Our formula is the channel analog of a well-known formula for the entanglement cost of quantum states in terms of the entanglement of formation; and shares a similar relation to the recently shattered hope for additivity. The entanglement cost of a quantum channel can be seen as the analog of the quantum reverse Shannon theorem in the case where free classical communication is allowed. The techniques used in the proof of our result are then also inspired by a recent proof of the quantum reverse Shannon theorem and feature the one-shot formalism for quantum information theory, the post-selection technique for quantum channels as well as von Neumann's minimax theorem. We discuss two applications of our result. First, we are able to link the security in the noisy-storage model to a problem of sending quantum rather than classical information through the adversary's storage device. This not only improves the range of parameters where security can be shown, but also allows us to prove security for storage devices for which no results were known before. Second, our result has consequences for the study of the strong converse quantum capacity. Here, we show that any coding scheme that sends quantum information through a quantum channel at a rate larger than the entanglement cost of the channel has an exponentially small fidelity.

Mario Berta; Fernando Brandao; Matthias Christandl; Stephanie Wehner

2011-08-26T23:59:59.000Z

386

A multiplexed quantum memory  

Science Journals Connector (OSTI)

A quantum repeater is a system for long-distance quantum communication that employs quantum memory elements to mitigate optical fiber transmission losses. The multiplexed quantum...

Lan, S -Y; Radnaev, A G; Collins, O A; Matsukevich, D N; Kennedy, T A; Kuzmich, A

2009-01-01T23:59:59.000Z

387

Active agents, intelligence and quantum Subhash Kak *  

E-Print Network (OSTI)

Active agents, intelligence and quantum computing Subhash Kak * Department of Electrical neuroscience and quantum computing theory in support of the notion of autonomy in the workings of cognitive processes. De®cits in speech, vision, and motor abilities are described to show how cognitive behavior

Kak, Subhash

388

Quantum Gravity Phenomenology and Lorentz Violation  

E-Print Network (OSTI)

If quantum gravity violates Lorentz symmetry, the prospects for observational guidance in understanding quantum gravity improve considerably. This article briefly reviews previous work on Lorentz violation (LV) and discusses aspects of the effective field theory framework for parametrizing LV effects. Current observational constraints on LV are then summarized, focusing on effects in QED at order E/M_Planck.

Ted Jacobson; Stefano Liberati; David Mattingly

2004-04-15T23:59:59.000Z

389

Born--Oppenheimer decomposition for quantum fields on quantum spacetimes  

E-Print Network (OSTI)

Quantum Field Theory on Curved Spacetime (QFT on CS) is a well established theoretical framework which intuitively should be a an extremely effective description of the quantum nature of matter when propagating on a given background spacetime. If one wants to take care of backreaction effects, then a theory of quantum gravity is needed. It is now widely believed that such a theory should be formulated in a non-perturbative and therefore background independent fashion. Hence, it is a priori a puzzle how a background dependent QFT on CS should emerge as a semiclassical limit out of a background independent quantum gravity theory. In this article we point out that the Born-Oppenheimer decomposition (BOD) of the Hilbert space is ideally suited in order to establish such a link, provided that the Hilbert space representation of the gravitational field algebra satisfies an important condition. If the condition is satisfied, then the framework of QFT on CS can be, in a certain sense, embedded into a theory of quantum gravity. The unique representation of the holonomy-flux algebra underlying Loop Quantum Gravity (LQG) violates that condition. While it is conceivable that the condition on the representation can be relaxed, for convenience in this article we consider a new classical gravitational field algebra and a Hilbert space representation of its restriction to an algebraic graph for which the condition is satisfied. An important question that remains and for which we have only partial answers is how to construct eigenstates of the full gravity-matter Hamiltonian whose BOD is confined to a small neighbourhood of a physically interesting vacuum spacetime.

Kristina Giesel; Johannes Tambornino; Thomas Thiemann

2009-11-27T23:59:59.000Z

390

Damped quantum harmonic oscillator  

E-Print Network (OSTI)

In the framework of the Lindblad theory for open quantum systems the damping of the harmonic oscillator is studied. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schr\\"odinger and Heisenberg representations of the Lindblad equation are given explicitly. On the basis of these representations it is shown that various master equations for the damped quantum oscillator used in the literature are particular cases of the Lindblad equation and that the majority of these equations are not satisfying the constraints on quantum mechanical diffusion coefficients. Analytical expressions for the first two moments of coordinate and momentum are also obtained by using the characteristic function of the Lindblad master equation. The master equation is transformed into Fokker-Planck equations for quasiprobability distributions. A comparative study is made for the Glauber $P$ representation, the antinormal ordering $Q$ representation and the Wigner $W$ representation. It is proven that the variances for the damped harmonic oscillator found with these representations are the same. By solving the Fokker-Planck equations in the steady state, it is shown that the quasiprobability distributions are two-dimensional Gaussians with widths determined by the diffusion coefficients. The density matrix is represented via a generating function, which is obtained by solving a time-dependent linear partial differential equation derived from the master equation. Illustrative examples for specific initial conditions of the density matrix are provided.

A. Isar; A. Sandulescu

2006-02-17T23:59:59.000Z

391

Orbits of hybrid systems as qualitative indicators of quantum dynamics  

E-Print Network (OSTI)

Hamiltonian theory of hybrid quantum-classical systems is used to study dynamics of the classical subsystem coupled to different types of quantum systems. It is shown that the qualitative properties of orbits of the classical subsystem clearly indicate if the quantum subsystem does or does not have additional conserved observables.

N. Buric; D. B. Popovic; M. Radonjic; S. Prvanovic

2014-03-03T23:59:59.000Z

392

Quantum metrology from a quantum information science perspective  

E-Print Network (OSTI)

We summarise important recent advances in quantum metrology, in connection to experiments in cold gases, trapped cold atoms and photons. First we review simple metrological setups, such as quantum metrology with spin squeezed states, with Greenberger-Horne-Zeilinger states, Dicke states and singlet states. We calculate the highest precision achievable in these schemes. Then, we present the fundamental notions of quantum metrology, such as shot-noise scaling, Heisenberg scaling, the quantum Fisher information and the Cramer-Rao bound. Using these, we demonstrate that entanglement is needed to surpass the shot-noise scaling in very general metrological tasks with a linear interferometer. We discuss some applications of the quantum Fisher information, such as how it can be used to obtain a criterion for a quantum state to be a macroscopic superposition. We show how it is related to the the speed of a quantum evolution, and how it appears in the theory of the quantum Zeno effect. Finally, we explain how uncorrela...

Toth, Geza

2015-01-01T23:59:59.000Z

393

Hybrid Quantum Mechanical and Molecular Mechanics Study of the SN2 Reaction of CCl4 + OH? in Aqueous Solution: The Potential of Mean Force, Reaction Energetics, and Rate Constants  

SciTech Connect

The bimolecular nucleophilic substitution reaction of CCl{sub 4} and OH{sup -} in aqueous solution was investigated on the basis of a combined quantum mechanical and molecular mechanics method. A multilayered representation approach is employed to achieve high accuracy results at the CCSD(T) level of theory. The potential of mean force calculations at the DFT level and CCSD(T) level of theory yield reaction barrier heights of 22.7 and 27.9 kcal/mol, respectively. Both the solvation effects and the solvent-induced polarization effect have significant contributions to the reaction energetics, for example, the solvation effect raises the saddle point by 10.6 kcal/mol. The calculated rate constant coefficient is 8.6 x 10{sup -28} cm{sup 3} molecule{sup -1} s{sup -1} at the standard state condition, which is about 17 orders magnitude smaller than that in the gas phase. Among the four chloromethanes (CH{sub 3}Cl, CH{sub 2}Cl{sub 2}, CHCl{sub 3}, and CCl{sub 4}), CCl{sub 4} has the lowest free energy activation barrier for the reaction with OH{sup -1} in aqueous solution, confirming the trend that substitution of Cl by H in chloromethanes diminishes the reactivity.

Wang, Ting; Yin, Hongyun; Wang, Dunyou; Valiev, Marat

2012-02-16T23:59:59.000Z

394

Dimensional reduction and quantum-to-classical reduction at high temperatures  

Science Journals Connector (OSTI)

We discuss the relation between dimensional reduction in quantum field theories at finite temperature and a familiar quantum-mechanical phenomenon that quantum effects become negligible at high temperatures. Fermi and Bose fields are compared in this respect. We show that decoupling of fermions from the dimensionally reduced theory can be related to the nonexistence of classical statistics for a Fermi field.

M. A. Stephanov

1995-09-15T23:59:59.000Z

395

Information and noise in quantum measurement  

Science Journals Connector (OSTI)

Even though measurement results obtained in the real world are generally both noisy and continuous, quantum measurement theory tends to emphasize the ideal limit of perfect precision and quantized measurement results. In this article, a more general concept of noisy measurements is applied to investigate the role of quantum noise in the measurement process. In particular, it is shown that the effects of quantum noise can be separated from the effects of information obtained in the measurement. However, quantum noise is required to cover up negative probabilities arising as the quantum limit is approached. These negative probabilities represent fundamental quantum-mechanical correlations between the measured variable and the variables affected by quantum noise.

Holger F. Hofmann

2000-07-06T23:59:59.000Z

396

Amplification, Redundancy, and the Quantum Chernoff Information  

E-Print Network (OSTI)

Amplification was regarded, since the early days of quantum theory, as a mysterious ingredient that endows quantum microstates with macroscopic consequences, key to the "collapse of the wavepacket", and a way to avoid embarrassing problems exemplified by Schr\\"odinger's cat. Such a bridge between the quantum microworld and the classical world of our experience was postulated ad hoc in the Copenhagen Interpretation. Quantum Darwinism views amplification as replication, in many copies, of the information about quantum states. We show that such amplification is a natural consequence of a broad class of models of decoherence, including the photon environment we use to obtain most of our information. This leads to objective reality via the presence of robust and widely accessible records of selected quantum states. The resulting redundancy (the number of copies deposited in the environment) follows from the Quantum Chernoff Information that quantifies the information transmitted by a typical elementary subsystem of the environment.

Michael Zwolak; C. Jess Riedel; Wojciech H. Zurek

2013-12-18T23:59:59.000Z

397

Prequantum Classical Statistical Field Theory: Fundamentals  

SciTech Connect

We present fundamentals of a prequantum model with hidden variables of the classical field type. In some sense this is the comeback of classical wave mechanics. Our approach also can be considered as incorporation of quantum mechanics into classical signal theory. All quantum averages (including correlations of entangled systems) can be represented as classical signal averages and correlations.

Khrennikov, Andrei [International Center for Mathematical Modelling in Physics and Cognitive Sciences, Linnaeus University, Vaexjoe, S-35195 (Sweden)

2011-03-28T23:59:59.000Z

398

Strong reactions in quantum super PDE's. I-II  

E-Print Network (OSTI)

This is a work in three parts, devoted to encode strong reactions of the high energy physics, in the algebraic topologic theory of quantum super PDE's, (previously formulated by A. Pr\\'astaro). In particular strong reactions are characterized by means of boundary value problems in quantum super PDE's. In such a way one obtains representations of quantum nonlinear propagators in quantum super PDE's, by means of elementary ones (quantum handle decompositions of quantum nonlinear propagators). These are useful to encode nuclear and subnuclear reactions in quantum physics. Pr\\'astaro's geometric theory of quantum PDE's allows us to obtain constructive and dynamically justified answers to some important open problems in high energy physics.

Agostino Prstaro

2015-02-01T23:59:59.000Z

399

Quantum fields in curved spacetime  

E-Print Network (OSTI)

We review the theory of quantum fields propagating in an arbitrary, classical, globally hyperbolic spacetime. Our review emphasizes the conceptual issues arising in the formulation of the theory and presents known results in a mathematically precise way. Particular attention is paid to the distributional nature of quantum fields, to their local and covariant character, and to microlocal spectrum conditions satisfied by physically reasonable states. We review the Unruh and Hawking effects for free fields, as well as the behavior of free fields in deSitter spacetime and FLRW spacetimes with an exponential phase of expansion. We review how nonlinear observables of a free field, such as the stress-energy tensor, are defined, as well as time-ordered-products. The "renormalization ambiguities" involved in the definition of time-ordered products are fully characterized. Interacting fields are then perturbatively constructed. Our main focus is on the theory of a scalar field, but a brief discussion of gauge fields is included. We conclude with a brief discussion of a possible approach towards a nonperturbative formulation of quantum field theory in curved spacetime and some remarks on the formulation of quantum gravity.

Stefan Hollands; Robert M. Wald

2014-06-10T23:59:59.000Z

400

Quantum friction  

E-Print Network (OSTI)

The Brownian motion of a light quantum particle in a heavy classical gas is theoretically described and a new expression for the friction coefficient is obtained for arbitrary temperature. At zero temperature it equals to the de Broglie momentum of the mean free path divided by the mean free path. Alternatively, the corresponding mobility of the quantum particle in the classical gas is equal to the square of the mean free path divided by the Planck constant. The Brownian motion of a quantum particle in a quantum environment is also discussed.

R. Tsekov

2012-03-12T23:59:59.000Z

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


401

Rovelli' s relational quantum mechanics, monism and quantum becoming  

E-Print Network (OSTI)

In this paper I present and defend Rovelli's relation quantum mechanics from some foreseeable objections, so as to clarify its philosophical implications vis a vis rival interpretations. In particular I ask whether RQM presupposes a hidden recourse to both a duality of evolutions and of ontology (the relationality of quantum world and the intrinsicness of the classical world, which in the limit must be recovered from the former). I then concentrate on the pluralistic, antimonistic metaphysical consequences of the theory, due to the impossibility of assigning a state to the quantum universe. Finally, in the last section I note interesting consequences of RQM with respect to the possibility of defining a local, quantum relativistic becoming (in flat spacetimes).Given the difficulties of having the cosmic form of becoming that would be appropriate for priority monism, RQM seems to present an important advantage with respect to monistic views, at least as far as the possibility of explaining our experience of time is concerned.

Mauro Dorato

2013-08-31T23:59:59.000Z

402

Quantum states prepared by realistic entanglement swapping  

E-Print Network (OSTI)

Entanglement swapping between photon pairs is a fundamental building block in schemes using quantum relays or quantum repeaters to overcome the range limits of long distance quantum key distribution. We develop a closed-form solution for the actual quantum states prepared by realistic entanglement swapping, which takes into account experimental deficiencies due to inefficient detectors, detector dark counts and multi-photon-pair contributions of parametric down conversion sources. We investigate how the entanglement present in the final state of the remaining modes is affected by the real-world imperfections. To test the predictions of our theory, comparison with experimental entanglement swapping is provided.

Scherer, Artur; Sanders, Barry C; Tittel, Wolfgang

2009-01-01T23:59:59.000Z

403

Quantum states prepared by realistic entanglement swapping  

E-Print Network (OSTI)

Entanglement swapping between photon pairs is a fundamental building block in schemes using quantum relays or quantum repeaters to overcome the range limits of long-distance quantum key distribution. We develop a closed-form solution for the actual quantum states prepared by realistic entanglement swapping, which takes into account experimental deficiencies due to inefficient detectors, detector dark counts, and multiphoton-pair contributions of parametric down-conversion sources. We investigate how the entanglement present in the final state of the remaining modes is affected by the real-world imperfections. To test the predictions of our theory, comparison with previously published experimental entanglement swapping is provided.

Artur Scherer; Regina B. Howard; Barry C. Sanders; Wolfgang Tittel

2009-04-07T23:59:59.000Z

404

An introduction to quantum machine learning  

E-Print Network (OSTI)

Machine learning algorithms learn a desired input-output relation from examples in order to interpret new inputs. This is important for tasks such as image and speech recognition or strategy optimisation, with growing applications in the IT industry. In the last couple of years, researchers investigated if quantum computing can help to improve classical machine learning algorithms. Ideas range from running computationally costly algorithms or their subroutines efficiently on a quantum computer to the translation of stochastic methods into the language of quantum theory. This contribution gives a systematic overview of the emerging field of quantum machine learning. It presents the approaches as well as technical details in an accessable way, and discusses the potential of a future theory of quantum learning.

M. Schuld; I. Sinayskiy; F. Petruccione

2014-09-10T23:59:59.000Z

405

Theory of correlated hops in surface diffusion  

Science Journals Connector (OSTI)

Scanning tunneling microscopy observations of long hops in the diffusion of Pb atoms on Ge surfaces are explained by the model of a Brownian particle in a periodic potential. The classical turnover theory for barrier crossing predicts a large correlated hopping probability in the underdamped limit, consistent with experiment and in agreement with simulations. The corresponding quantum theory predicts that in the underdamped limit the rate is dominated by tunneling. This causes the quantum correlated hopping probability to vanish in this limit and may be thought of as a new form of quantum localization.

Eli Pollak, Joel Bader, B. J. Berne, and Peter Talkner

1993-05-24T23:59:59.000Z

406

Quantum Quandaries: A Category-Theoretic Perspective  

E-Print Network (OSTI)

and water. However, work on topological quantum field theory theory has uncovered a deep analogy between revealed a deep analogy between the two. General relativity makes heavy use of the cat- egory nCob, whose basic concepts. By now it is almost a truism that the project of quantizing gravity may force us

Baez, John

407

Quantum Quandaries: A CategoryTheoretic Perspective  

E-Print Network (OSTI)

and water. However, work on topological quantum field theory theory has uncovered a deep analogy between revealed a deep analogy between the two. General relativity makes heavy use of the cat­ egory nCob, whose basic concepts. By now it is almost a truism that the project of quantizing gravity may force us

Baez, John

408

Quantum Graphical Models and Belief Propagation  

SciTech Connect

Belief Propagation algorithms acting on Graphical Models of classical probability distributions, such as Markov Networks, Factor Graphs and Bayesian Networks, are amongst the most powerful known methods for deriving probabilistic inferences amongst large numbers of random variables. This paper presents a generalization of these concepts and methods to the quantum case, based on the idea that quantum theory can be thought of as a noncommutative, operator-valued, generalization of classical probability theory. Some novel characterizations of quantum conditional independence are derived, and definitions of Quantum n-Bifactor Networks, Markov Networks, Factor Graphs and Bayesian Networks are proposed. The structure of Quantum Markov Networks is investigated and some partial characterization results are obtained, along the lines of the Hammersley-Clifford theorem. A Quantum Belief Propagation algorithm is presented and is shown to converge on 1-Bifactor Networks and Markov Networks when the underlying graph is a tree. The use of Quantum Belief Propagation as a heuristic algorithm in cases where it is not known to converge is discussed. Applications to decoding quantum error correcting codes and to the simulation of many-body quantum systems are described.

Leifer, M.S. [Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, Waterloo Ont., N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo Ont., N2L 2Y5 (Canada)], E-mail: matt@mattleifer.info; Poulin, D. [Center for the Physics of Information, California Institute of Technology, 1200 E. California Boulevard, 107-81, Pasadena, CA 91125 (United States)], E-mail: dpoulin@ist.caltech.edu

2008-08-15T23:59:59.000Z

409

Algebraic and information-theoretic conditions for operator quantum error correction  

SciTech Connect

Operator quantum error correction is a technique for robustly storing quantum information in the presence of noise. It generalizes the standard theory of quantum error correction, and provides a unified framework for topics such as quantum error correction, decoherence-free subspaces, and noiseless subsystems. This paper develops (a) easily applied algebraic and information-theoretic conditions that characterize when operator quantum error correction is feasible; (b) a representation theorem for a class of noise processes that can be corrected using operator quantum error correction; and (c) generalizations of the coherent information and quantum data processing inequality to the setting of operator quantum error correction.

Nielsen, Michael A.; Poulin, David [School of Physical Sciences, University of Queensland, Queensland 4072 (Australia)

2007-06-15T23:59:59.000Z

410

Algebraic and information-theoretic conditions for operator quantum error correction  

Science Journals Connector (OSTI)

Operator quantum error correction is a technique for robustly storing quantum information in the presence of noise. It generalizes the standard theory of quantum error correction, and provides a unified framework for topics such as quantum error correction, decoherence-free subspaces, and noiseless subsystems. This paper develops (a) easily applied algebraic and information-theoretic conditions that characterize when operator quantum error correction is feasible; (b) a representation theorem for a class of noise processes that can be corrected using operator quantum error correction; and (c) generalizations of the coherent information and quantum data processing inequality to the setting of operator quantum error correction.

Michael A. Nielsen and David Poulin

2007-06-21T23:59:59.000Z

411

Quantum Exclusion of Positive Cosmological Constant?  

E-Print Network (OSTI)

We show that a positive cosmological constant is incompatible with the quantum-corpuscular resolution of de Sitter metric in form of a coherent state. The reason is very general and is due to the quantum self-destruction of the coherent state because of the scattering of constituent graviton quanta. This process creates an irreversible quantum clock, which precludes eternal de Sitter. It also eliminates the possibility of Boltzmann brains and Poincare recurrences. This effect is expected to be part of any microscopic theory that takes into account the quantum corpuscular structure of the cosmological background. This observation puts the cosmological constant problem in a very different light, promoting it, from a naturalness problem, into a question of quantum consistency. We are learning that quantum gravity cannot tolerate exceedingly-classical sources.

Gia Dvali; Cesar Gomez

2014-12-27T23:59:59.000Z

412

Quantum Structures of the Hydrogen Atom  

E-Print Network (OSTI)

Modern quantum theory introduces quantum structures (decompositions into subsystems) as a new discourse that is not fully comparable with the classical-physics counterpart. To this end, so-called Entanglement Relativity appears as a corollary of the universally valid quantum mechanics that can provide for a deeper and more elaborate description of the composite quantum systems. In this paper we employ this new concept to describe the hydrogen atom. We offer a consistent picture of the hydrogen atom as an open quantum system that naturally answers the following important questions: (a) how do the so called "quantum jumps" in atomic excitation and de-excitation occur? and (b) why does the classically and seemingly artificial "center-of-mass + relative degrees of freedom" structure appear as the primarily operable form in most of the experimental reality of atoms?

J. Jeknic-Dugic; M. Dugic; A. Francom; M. Arsenijevic

2014-05-28T23:59:59.000Z

413

Experimental entanglement-assisted quantum delayed-choice experiment  

E-Print Network (OSTI)

The puzzling properties of quantum mechanics, wave-particle duality, entanglement and superposition, were dissected experimentally at past decades. However, hidden-variable (HV) models, based on three classical assumptions of wave-particle objectivity, determinism and independence, strive to explain or even defeat them. The development of quantum technologies enabled us to test experimentally the predictions of quantum mechanics and HV theories. Here, we report an experimental demonstration of an entanglement-assisted quantum delayed-choice scheme using a liquid nuclear magnetic resonance quantum information processor. This scheme we realized is based on the recently proposed scheme [Nat. Comms. 5:4997(2014)], which gave different results for quantum mechanics and HV theories. In our experiments, the intensities and the visibilities of the interference are in consistent the theoretical prediction of quantum mechanics. The results imply that a contradiction is appearing when all three assumptions of HV models are combined, though any two of the above assumptions are compatible with it.

Tao Xin; Hang Li; Bi-Xue Wang; Gui-Lu Long

2014-11-30T23:59:59.000Z

414

Quantum theory of bilayer quantum Hall smectics Emiliano Papa,1  

E-Print Network (OSTI)

of charge-density and position along each stripe edge. The soft modes associated with the broken symmetries spontaneous interlayer phase coherence and a sizable charge gap even at relatively large layer separations in very high mobility bilayer systems at dilution refrigerator temperatures as a function of layer

415

Gravity and the Quantum: Are they Reconcilable?  

E-Print Network (OSTI)

General relativity and quantum mechanics are conflicting theories. The seeds of discord are the fundamental principles on which these theories are grounded. General relativity, on one hand, is based on the equivalence principle, whose strong version establishes the local equivalence between gravitation and inertia. Quantum mechanics, on the other hand, is fundamentally based on the uncertainty principle, which is essentially nonlocal in the sense that a particle does not follow one trajectory, but infinitely many trajectories, each one with a different probability. This difference precludes the existence of a quantum version of the strong equivalence principle, and consequently of a quantum version of general relativity. Furthermore, there are compelling experimental evidences that a quantum object in the presence of a gravitational field violates the weak equivalence principle. Now it so happens that, in addition to general relativity, gravitation has an alternative, though equivalent description, given by teleparallel gravity, a gauge theory for the translation group. In this theory torsion, instead of curvature, is assumed to represent the gravitational field. These two descriptions lead to the same classical results, but are conceptually different. In general relativity, curvature geometrizes the interaction, while torsion in teleparallel gravity acts as a force, similar to the Lorentz force of electrodynamics. Because of this peculiar property, teleparallel gravity describes the gravitational interaction without requiring any of the equivalence principles. The replacement of general relativity by teleparallel gravity may, in consequence, lead to a conceptual reconciliation of gravitation with quantum mechanics.

R. Aldrovandi; J. G. Pereira; K. H. Vu

2005-09-14T23:59:59.000Z

416

Dicarboxylate assisted synthesis of the monoclinic heterometallic tetrathiocyanato bridged copper(II) and mercury(II) coordination polymer {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n}: Synthesis, structural, vibration, luminescence, EPR studies and DFT calculations  

SciTech Connect

The synthesis of the monoclinic polymorph of {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n} is reported. The compound, as determined by X-ray diffraction of a twinned crystal, consists of mercury and copper atoms linked by {mu}{sub 1,3}-SCN bridges. The crystal packing shows a highly porous infinite 3D structure. Diagnostic resonances for the SCN{sup -} ligand and metal-ligand bonds in the IR, far-IR and Raman spectra are assigned and discussed. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that the compound is an indirect band gap semiconductor. The DFT calculations show that the observed luminescence of the compound arises mainly from an excited LLCT state with small MLCT contributions (from the copper to unoccupied {pi}{sup *} orbital of the thiocyanate groups). The X-band EPR spectrum of the powdered sample at room temperature reveals an axial signal with anisotropic g factors consistent with the unpaired electron of Cu(II) ion in the d{sub x}{sup 2}{sub -y}{sup 2} orbital. -- Graphical abstract: Synthesis and X-ray structure determination of the monoclinic {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n} is reported. The IR, far-IR, Raman, photoluminescence as well as EPR spectra of the compound is discussed. Also, the emission and semiconducting behavior of the compound is illustrated through the density functional theory calculation of electronic band structure along with density of states. Display Omitted Research highlights: > The monoclinic {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n} has been prepared. > The structure of the compound is determined by XRD of a twinned crystal. > The IR, far-IR, Raman, EPR and emission spectra of the compound is investigated. > As shown by DFT calculations, the emission bands of the compound are mainly LLCT. > Small MLCT from the copper to the thiocyanate groups contributes to these bands.

Khandar, Ali Akbar, E-mail: akhandar@yahoo.co [Department of Inorganic Chemistry, Faculty of Chemistry, University of Tabriz, 5166614766 Tabriz (Iran, Islamic Republic of); Klein, Axel [Institut fuer Anorganische Chemie, Universitaet zu Koeln, Greinstrasse 6, 50939 Koeln (Germany); Bakhtiari, Akbar [Department of Inorganic Chemistry, Faculty of Chemistry, University of Tabriz, 5166614766 Tabriz (Iran, Islamic Republic of); Institut fuer Anorganische Chemie, Universitaet zu Koeln, Greinstrasse 6, 50939 Koeln (Germany); Mahjoub, Ali Reza [Department of Chemistry, School of Science, Tarbiat Modares University, P.O. Box 14155-4838 Tehran (Iran, Islamic Republic of); Pohl, Roland W.H. [Institut fuer Anorganische Chemie, Universitaet zu Koeln, Greinstrasse 6, 50939 Koeln (Germany)

2011-02-15T23:59:59.000Z

417

Adaptive hybrid optimal quantum control for imprecisely characterized systems  

E-Print Network (OSTI)

Optimal quantum control theory carries a huge promise for quantum technology. Its experimental application, however, is often hindered by imprecise knowledge of the its input variables, the quantum system's parameters. We show how to overcome this by Adaptive Hybrid Optimal Control (Ad-HOC). This protocol combines open- and closed-loop optimal by first performing a gradient search towards a near-optimal control pulse and then an experimental fidelity measure with a gradient-free method. For typical settings in solid-state quantum information processing, Ad-Hoc enhances gate fidelities by an order of magnitude hence making optimal control theory applicable and useful.

D. J. Egger; F. K. Wilhelm

2014-02-28T23:59:59.000Z

418

On a super-selection rule in quantum cosmology  

E-Print Network (OSTI)

The discarding of negative frequency solutions in a quantum field theory brings about the absence of antiparticles which, after all, means the violation of 4-inversion symmetry $(x \\rightarrow -x, t \\rightarrow-t)$ which is a (improper) Lorentz transformation. Suppose you have a theory of quantum gravity which lacks the negative frequency solutions (like usually people have in quantum cosmology, invoking a super-selection rule). Taking some limit in this theory in order to obtain the weak (or null) gravitational regime, the result is a theory that does not respect that symmetry and does not have place for antiparticles. That is, a theory of fields is not obtained, as it should be. For the case of a quantum cosmology model we show that if we ignore the negative frequency solutions, the rich processes of creation/annihilation of universes at the Planck scale, are lost.

E. Sergio Santini

2014-12-26T23:59:59.000Z

419

Probabilistic theories with purification  

SciTech Connect

We investigate general probabilistic theories in which every mixed state has a purification, unique up to reversible channels on the purifying system. We show that the purification principle is equivalent to the existence of a reversible realization of every physical process, that is, to the fact that every physical process can be regarded as arising from a reversible interaction of the system with an environment, which is eventually discarded. From the purification principle we also construct an isomorphism between transformations and bipartite states that possesses all structural properties of the Choi-Jamiolkowski isomorphism in quantum theory. Such an isomorphism allows one to prove most of the basic features of quantum theory, like, e.g., existence of pure bipartite states giving perfect correlations in independent experiments, no information without disturbance, no joint discrimination of all pure states, no cloning, teleportation, no programming, no bit commitment, complementarity between correctable channels and deletion channels, characterization of entanglement-breaking channels as measure-and-prepare channels, and others, without resorting to the mathematical framework of Hilbert spaces.

Chiribella, Giulio; D'Ariano, Giacomo Mauro; Perinotti, Paolo [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Ontario, Ontario N2L 2Y5 (Canada); QUIT Group, Dipartimento di Fisica ''A. Volta'' and INFN Sezione di Pavia, via Bassi 6, 27100 Pavia (Italy)

2010-06-15T23:59:59.000Z

420

The Superposition Principle in Quantum Mechanics - did the rock enter the foundation surreptitiously?  

E-Print Network (OSTI)

The superposition principle forms the very backbone of quantum theory. The resulting linear structure of quantum theory is structurally so rigid that tampering with it may have serious, seemingly unphysical, consequences. This principle has been succesful at even the highest available accelerator energies. Is this aspect of quantum theory forever then? The present work is an attempt to understand the attitude of the founding fathers, particularly of Bohr and Dirac, towards this principle. The Heisenberg matrix mechanics on the one hand, and the Schrodinger wave mechanics on the other, are critically examined to shed light as to how this principle entered the very foundations of quantum theory.

N. D. Hari Dass

2013-11-18T23:59:59.000Z

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


421

The Superposition Principle in Quantum Mechanics - did the rock enter the foundation surreptitiously?  

E-Print Network (OSTI)

The superposition principle forms the very backbone of quantum theory. The resulting linear structure of quantum theory is structurally so rigid that tampering with it may have serious, seemingly unphysical, consequences. This principle has been succesful at even the highest available accelerator energies. Is this aspect of quantum theory forever then? The present work is an attempt to understand the attitude of the founding fathers, particularly of Bohr and Dirac, towards this principle. The Heisenberg matrix mechanics on the one hand, and the Schrodinger wave mechanics on the other, are critically examined to shed light as to how this principle entered the very foundations of quantum theory.

Dass, N D Hari

2013-01-01T23:59:59.000Z

422

Next steps in understanding the asymptotics of $3d$ quantum gravity  

E-Print Network (OSTI)

Based on a combinatorial approach and random matrix theory, we show a central limit theorem that gives important insight into causally triangulated $3d$ quantum gravity.

Maria Simonetta Bernabei; Horst Thaler

2014-12-10T23:59:59.000Z

423

Quantum Measurements: a modern view for quantum optics experimentalists  

E-Print Network (OSTI)

In these notes, based on lectures given as part of the Les Houches summer school on Quantum Optics and Nanophotonics in August, 2013, I have tried to give a brief survey of some important approaches and modern tendencies in quantum measurement. I wish it to be clear from the outset that I shy explicitly away from the "quantum measurement problem," and that the present treatment aims to elucidate the theory and practice of various ways in which measurements can, in light of quantum mechanics, be carried out; and various formalisms for describing them. While the treatment is by necessity largely theoretical, the emphasis is meant to be on an experimental "perspective" on measurement -- that is, to place the priority on the possibility of gaining information through some process, and then attempting to model that process mathematically and consider its ramifications, rather than stressing a particular mathematical definition as the {\\it sine qua non} of measurement. The textbook definition of measurement as being a particular set of mathematical operations carried out on particular sorts of operators has been so well drilled into us that many have the unfortunate tendency of saying "that experiment can't be described by projections onto the eigenstates of a Hermitian operator, so it is not really a measurement," when of course any practitioner of an experimental science such as physics should instead say "that experiment allowed us to measure something, and if the standard theory of measurement does not describe it, the standard theory of measurement is incomplete." Idealisations are important, but when the real world breaks the approximations made in the theory, it is the theory which must be fixed, and not the real world.

Aephraim M. Steinberg

2014-06-20T23:59:59.000Z

424

Quantum Tachyon Dynamics  

E-Print Network (OSTI)

It is suggested that charged tachyons of extremely large mass M could not only contribute to the dark matter needed to fit astrophysical observations, but could also provide an explanation for gamma ray bursts and ulta high energy cosmic rays. The present paper defines a quantum field theory of tachyons, particles similar to ordinary leptons, but with momenta larger than energy. The theory is invariant under the full CPT transformation, but separately violates P and T invariance. Micro causality is broken for space-time intervals smaller than 1/M, but is effectively preserved for larger separations. Charged fermionic, rather than charged scalar tachyons are considered in order to minimize the probability of Cerenkov-like radiation by the tachyon, thereby permitting a high energy tachyon to retain its energy over galactic distances. Topics treated include the choice and Schwinger Action Principle variations of an appropriate Lagrangian, spinorial wave functions, relevant Green's functions, a functional descrip...

Fried, H M

2007-01-01T23:59:59.000Z

425

Wonderful Compactifications in Quantum Field Theory  

E-Print Network (OSTI)

This article reviews the use of DeConcini-Procesi wonderful models in renormalization of ultraviolet divergences in position space as introduced by Bergbauer, Brunetti and Kreimer. In contrast to the exposition there we employ a slightly different approach; instead of the subspaces in the arrangement of divergent loci, we use the poset of divergent subgraphs as the main tool to describe the whole renormalization process. This is based on an article by Feichtner, where wonderful models were studied from a purely combinatorial viewpoint. The main motivation for this approach is the fact that both, renormalization and the model construction, are governed by the combinatorics of this poset. Not only simplifies this the exposition considerably, but also allows to study the renormalization operators in more detail. Moreover, we explore the renormalization group in this setting by studying how the renormalized distributions behave under a change of renormalization points.

Marko Berghoff

2015-02-02T23:59:59.000Z

426

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

at Midway station send signals to both at the same time, so that Alice receives hers when she reaches Europa

427

THEORY OF QUANTUM-MECHANICAL DESCRIPTION  

Science Journals Connector (OSTI)

...classes for all scientific methodology has repeatedly been...rules of the operator calculus one can assign a probability...by maximizing S with subsidiary conditions. The conditions...of the conventional methodology of physical science...

Walter M. Elsasser

1968-01-01T23:59:59.000Z

428

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

's Constant Newton's constant G appears in the universal law of gravitation: It determines the strength potential energy that we see as mass a spontaneously broken symmetry is a symmetry of the laws of nature. An object of mass m in a gravitational field g feels a force of F = mg This is similar to electromagnetism

429

Theory of Quantum Oscillations in Cuprate Superconductors  

E-Print Network (OSTI)

High Temperature Cuprate Superconductors . . . . . . . . . . . . . . . . . .the underdoped high temperature superconductor YBa 2 Cu 3 Oorder in the high-temperature superconductor yba 2 cu 3 o

Eun, Jonghyoun

2012-01-01T23:59:59.000Z

430

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

electric fields to accelerate the particles and magnetic fields to control their directions detectors particles, the nuclear force) neutrinos (beta decay, conservation laws, particle stability) Thursday, May 7 these states exist, but they are all filled. Redefine the vacuum as this situation: define this as a zero

431

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

electron/positron pairs in the vacuum shield electromagnetic charges, making them seem smaller than for a while it looked like we were close to a complete picture, with just the electromagnetic and nuclear forces, and the particles from last time In the 1950s and 60s accelerator and cosmic ray experiments

432

Is there a Jordan geometry underlying quantum physics?  

E-Print Network (OSTI)

There have been several propositions for a geometric and essentially non-linear formulation of quantum mechanics. From a purely mathematical point of view, the point of view of Jordan algebra theory might give new strength to such approaches: there is a ``Jordan geometry'' belonging to the Jordan part of the algebra of observables, in the same way as Lie groups belong to the Lie part. Both the Lie geometry and the Jordan geometry are well-adapted to describe certain features of quantum theory. We concentrate here on the mathematical description of the Jordan geometry and raise some questions concerning possible relations with foundational issues of quantum theory.

Wolfgang Bertram

2008-01-20T23:59:59.000Z

433

The Quantum Vacuum and the Cosmological Constant Problem  

E-Print Network (OSTI)

The cosmological constant problem arises at the intersection between general relativity and quantum field theory, and is regarded as a fundamental problem in modern physics. In this paper we describe the historical and conceptual origin of the cosmological constant problem which is intimately connected to the vacuum concept in quantum field theory. We critically discuss how the problem rests on the notion of physical real vacuum energy, and which relations between general relativity and quantum field theory are assumed in order to make the problem well-defined.

Svend Erik Rugh; Henrik Zinkernagel

2000-12-28T23:59:59.000Z

434

The Quantum Vacuum and the Cosmological Constant Problem  

E-Print Network (OSTI)

The cosmological constant problem arises at the intersection between general relativity and quantum field theory, and is regarded as a fundamental problem in modern physics. In this paper we describe the historical and conceptual origin of the cosmological constant problem which is intimately connected to the vacuum concept in quantum field theory. We critically discuss how the problem rests on the notion of physical real vacuum energy, and which relations between general relativity and quantum field theory are assumed in order to make the problem well-defined.

Rugh, S E; Rugh, Svend Erik; Zinkernagel, Henrik

2000-01-01T23:59:59.000Z

435

A Guided Tour of TimeDependent Density Functional Theory  

E-Print Network (OSTI)

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

Gross, E.K.U.

436

Classical versus quantum coherence  

Science Journals Connector (OSTI)

...M. Stoneham Classical versus quantum coherence P. T. Greenland Department of Physics...nanostructures| Classical versus quantum coherence. | Quantum dots are structures engineered...2002.1134 Classical versus quantum coherence By P. T. Greenland Department of Physics...

2003-01-01T23:59:59.000Z

437

Quantum Chromodynamics and nuclear physics at extreme energy density. Progress report, May 1992--April 1993  

SciTech Connect

This report discusses research in the following topics: Hadron structure physics; relativistic heavy ion collisions; finite- temperature QCD; real-time lattice gauge theory; and studies in quantum field theory.

Mueller, B.

1993-05-15T23:59:59.000Z

438

Nonequilibrium quantum statistical mechanics and thermodynamics  

E-Print Network (OSTI)

The purpose of this work is to discuss recent progress in deriving the fundamental laws of thermodynamics (0th, 1st and 2nd-law) from nonequilibrium quantum statistical mechanics. Basic thermodynamic notions are clarified and different reversible and irreversible thermodynamic processes are studied from the point of view of quantum statistical mechanics. Special emphasis is put on new adiabatic theorems for steady states close to and far from equilibrium, and on investigating cyclic thermodynamic processes using an extension of Floquet theory.

Walid K. Abou Salem

2006-01-23T23:59:59.000Z

439

Quantum capacity of channel with thermal noise  

E-Print Network (OSTI)

The quantum capacity of thermal noise channel is studied. The extremal input state is obtained at the postulation that the coherent information is convex or concave at its vicinity. When the input energy tends to infinitive, it is verified by perturbation theory that the coherent information reaches its maximum at the product of identical thermal state input. The quantum capacity is obtained for lower noise channel and it is equal the one shot capacity.

Xiao-yu Chen

2006-02-11T23:59:59.000Z

440

Quantum computing in a piece of glass  

E-Print Network (OSTI)

Quantum gates and simple quantum algorithms can be designed utilizing the diffraction phenomena of a photon within a multiplexed holographic element. The quantum eigenstates we use are the photon's linear momentum (LM) as measured by the number of waves of tilt across the aperture. Two properties of quantum computing within the circuit model make this approach attractive. First, any conditional measurement can be commuted in time with any unitary quantum gate - the timeless nature of quantum computing. Second, photon entanglement can be encoded as a superposition state of a single photon in a higher-dimensional state space afforded by LM. Our theoretical and numerical results indicate that OptiGrate's photo-thermal refractive (PTR) glass is an enabling technology. We will review our previous design of a quantum projection operator and give credence to this approach on a representative quantum gate grounded on coupled-mode theory and numerical simulations, all with parameters consistent with PTR glass. We discuss the strengths (high efficiencies, robustness to environment) and limitations (scalability, crosstalk) of this technology. While not scalable, the utility and robustness of such optical elements for broader quantum information processing applications can be substantial.

Warner A. Miller; Grigoriy Kreymerman; Christopher Tison; Paul M. Alsing; Jonathan R. McDonald

2011-12-15T23:59:59.000Z

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


441

Fundamental measure theory for the electric double layer: applications to blue-energy harvesting and water desalination  

E-Print Network (OSTI)

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 electrodes at voltages of the order of hundreds of millivolts, such that counter-ionic packing is important. We propose a density functional theory (DFT) to model the electric double layer which forms near the surfaces of these porous materials. The White-Bear mark II fundamental measure theory (FMT) functional is combined with a mean-field Coulombic and a MSA-type correction to describe the interplay between dense packing and electrostatics, in good agreement with MD simulations. 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.

Andreas Hrtel; Mathijs Janssen; Sela Samin; Ren van Roij

2014-11-20T23:59:59.000Z

442

Statistical atom: Some quantum improvements  

Science Journals Connector (OSTI)

The Thomas-Fermi model is improved by simultaneously introducing three different quantum corrections. The first concerns the nonlocality of quantum mechanics; we go beyond the von Weizscker approach by including arbitrary powers of the gradient of the single-particle potential. The second is a special treatment of the strongly bound electrons, which removes the incorrect statistical description of the vicinity of the nucleus. In the third we generalize Dirac's way of handling the exchange interaction by, again, including gradient effects to arbitrary order. All this is done in the framework of a "potential-functional method" and results in a new differential equation for the potential. The comparison of numerical results with both experimental and Hartree-Fock data for the mean-squared distance indicates a superiority of the new statistical theory over the Hartree-Fock theory, at least for the description of the outer reaches of the atom.

Berthold-Georg Englert and Julian Schwinger

1984-05-01T23:59:59.000Z

443

CNM Highlight: Quantum Dot-Induced Transparency  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum Dot-Induced Transparency Quantum Dot-Induced Transparency Using rigorous and realistic numerical simulations, staff in the Nanophotonics and Theory and Modeling groups have recently demonstrated that a single semiconductor nanocrystal, or quantum dot, can cancel the scattering and absorption by a much larger metal nanostructure. Placing a quantum dot near a metal is known to strongly modify the rate at which the dot emits light. If the interaction between the dot and the metal is strong enough, scattering and absorption by the metal can be nearly eliminated at the quantum-dot resonance frequency, according to the simulations. This occurs even though the dot by itself simply absorbs light, and even though this absorption is nearly 100,000 times smaller than absorption by the metal nanostructure.

444

Quantum Mechanical Search and Harmonic Perturbation  

E-Print Network (OSTI)

Perturbation theory in quantum mechanics studies how quantum systems interact with their environmental perturbations. Harmonic perturbation is a rare special case of time-dependent perturbations in which exact analysis exists. Some important technology advances, such as masers, lasers, nuclear magnetic resonance, etc., originated from it. Here we add quantum computation to this list with a theoretical demonstration. Based on harmonic perturbation, a quantum mechanical algorithm is devised to search the ground state of a given Hamiltonian. The intrinsic complexity of the algorithm is continuous and parametric in both time T and energy E. More precisely, the probability of locating a search target of a Hamiltonian in N-dimensional vector space is shown to be 1/(1+ c N E^{-2} T^{-2}) for some constant c. This result is optimal. As harmonic perturbation provides a different computation mechanism, the algorithm may suggest new directions in realizing quantum computers.

Jie-Hong R. Jiang; Dah-Wei Chiou; Cheng-En Wu

2007-02-01T23:59:59.000Z

445

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

SciTech Connect

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

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

2014-05-14T23:59:59.000Z

446

Loop quantum gravity - a short review  

E-Print Network (OSTI)

In this article we review the foundations and the present status of loop quantum gravity. It is short and relatively non-technical, the emphasis is on the ideas, and the flavor of the techniques. In particular, we describe the kinematical quantization and the implementation of the Hamilton constraint, as well as the quantum theory of black hole horizons, semiclassical states, and matter propagation. Spin foam models and loop quantum cosmology are mentioned only in passing, as these will be covered in separate reviews to be published alongside this one.

Sahlmann, Hanno

2010-01-01T23:59:59.000Z

447

Quantum Measurement and the Paulian Idea  

E-Print Network (OSTI)

In the quantum Bayesian (or QBist) conception of quantum theory, "quantum measurement" is understood not as a comparison of something pre-existent with a standard, but instead indicative of the creation of something new in the universe: Namely, the fresh experience any agent receives upon taking an action on the world. We explore the implications of this for any would-be ontology underlying QBism. The concept that presently stands out as a candidate "material for our universe's composition" is "experience" itself, or what John Wheeler called "observer-participancy".

Christopher Fuchs; Ruediger Schack

2014-12-16T23:59:59.000Z

448

AdS/CFT and Light-Front Holography: A Theory of Strong Interactions  

SciTech Connect

Recent developments in the theory of strong interactions are discussed in the framework of the AdS/CFT duality between string theories of gravity in a higher dimension Anti-de Sitter space and conformal quantum field theories in physical space-time. This novel theoretical approach, combined with 'light-front holography', leads to new insights into the quark and gluon structure of hadrons and a viable first approximation to quantum chromodynamics, the fundamental theory of the strong and nuclear interactions.

Brodsky, Stanley J.; /SLAC; Teramond, Guy F.de; /Costa Rica U.

2009-02-23T23:59:59.000Z

449

EPR, Bell, GHZ, and Hardy theorems, and quantum mechanics  

E-Print Network (OSTI)

We review the theorems of Einstein-Podolsky-Rosen (EPR), Bell, Greenberger-Horne-Zeilinger (GHZ), and Hardy, and present arguments supporting the idea that quantum mechanics is a complete, causal, non local, and non separable theory.

Miguel Socolovsky

2005-08-09T23:59:59.000Z

450

A quantum gravitational origin of dark energy  

E-Print Network (OSTI)

We propose a new explanation of the origin of the small vacuum energy of the present universe within a nonperturbative quantum theory of gravity with torsional instantons. These pseudoparticles, which were recently found to exist in a first order formulation of Giddings-Strominger axionic gravity, carry nontrivial Nieh-Yan topological charge. The nonperturbative vacuum as generated due to tunneling effects and parametrised by the Barbero-Immirzi topological angle is shown to be stable under quantum fluctuations. In this theory, absence of any observable parity violating effect fixes the Barbero-Immirzi parameter to a small value, which is determined by the current estimate of the Hubble constant.

Sengupta, Sandipan

2015-01-01T23:59:59.000Z

451

A Novel, Green Technology for the Production of Aromatic Thiol from Aromatic Sulfonyl Chloride  

E-Print Network (OSTI)

Functional Theory (DFT), a quantum mechanical method, was used to investigate the new aromatic thiol production technology at the molecular level in aspects including reaction species adsorption and transition state determination. Plant design methods...

Atkinson, Bradley R.

2010-01-16T23:59:59.000Z

452

A Polarizable QM/MM Explicit Solvent Model for Computational Electrochemistry in Water  

E-Print Network (OSTI)

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 ...

Wang, Lee-Ping

453

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

E-Print Network (OSTI)

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

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

2014-01-01T23:59:59.000Z

454

Loop quantum cosmology in 2+1 dimension  

E-Print Network (OSTI)

As a first step to generalize the structure of loop quantum cosmology to the theories with the spacetime dimension other than four, the isotropic model of loop quantum cosmology in 2+1 dimension is studied in this paper. We find that the classical big bang singularity is again replaced by a quantum bounce in the model. The similarities and differences between the 2+1 dimensional model and the 3+1 dimensional one are also discussed.

Xiangdong Zhang

2014-11-19T23:59:59.000Z

455

Macroscopic quantum tunnelling in a current biased Josephson junction  

SciTech Connect

We discuss in this work an attempt to answer experimentally the question: do macroscopic variables obey quantum mechanics. More precisely, this experiment deals with the question of quantum-mechanical tunnelling of a macroscopic variable, a subject related to the famous Schrodinger's cat problem in the theory of measurement.

Martinis, J.M.; Devoret, M.H.; Clarke, J.; Urbina, C.

1984-11-01T23:59:59.000Z

456

Spectral Analysis of an Effective Hamiltonian in Nonrelativistic Quantum  

E-Print Network (OSTI)

Department of Mathematics, Hokkaido University Sapporo 060-0810 Japan E-mail: arai with the quantum radiation field (for reviews on recent developments of mathematical theory of nonrelativistic QED with the quantum radiation field. This kind of approach (heuristic) was first given by Welton [14], based

457

Green's Functions and Their Applications to Quantum Mechanics  

E-Print Network (OSTI)

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

Morrow, James A.

458

Manifestations of quantum phase transitions in transport through nanosystems  

SciTech Connect

The award led to several important new results in theory of interacting low-dimensional systems. The results are relevant for both traditional condensed matter systems, such as quantum wires and quantum spin chains, and for the relatively new field of ultra-cold atomic gases.

Pustilnik, Michael

2014-08-28T23:59:59.000Z

459

Viscosity of an ideal relativistic quantum fluid: A perturbative study  

E-Print Network (OSTI)

We show that a quantized ideal fluid will generally exhibit a small but non-zero viscosity due to the backreaction of quantum soundwaves on the background. We use an effective field theory expansion to estimate this viscosity to first order in perturbation theory. We discuss our results, and whether this estimate can be used to obtain a more model-independent estimate of the "quantum bound" on the viscosity of physical systems

Giorgio Torrieri

2011-12-17T23:59:59.000Z

460

Optical Abelian Lattice Gauge Theories  

E-Print Network (OSTI)

We discuss a general framework for the realization of a family of abelian lattice gauge theories, i.e., link models or gauge magnets, in optical lattices. We analyze the properties of these models that make them suitable to quantum simulations. Within this class, we study in detail the phases of a U(1)-invariant lattice gauge theory in 2+1 dimensions originally proposed by Orland. By using exact diagonalization, we extract the low-energy states for small lattices, up to 4x4. We confirm that the model has two phases, with the confined entangled one characterized by strings wrapping around the whole lattice. We explain how to study larger lattices by using either tensor network techniques or digital quantum simulations with Rydberg atoms loaded in optical lattices where we discuss in detail a protocol for the preparation of the ground state. We also comment on the relation between standard compact U(1) LGT and the model considered.

L. Tagliacozzo; A. Celi; A. Zamora; M. Lewenstein

2013-02-07T23:59:59.000Z

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


461

Quantum++ - A C++11 quantum computing library  

E-Print Network (OSTI)

Quantum++ is a general-purpose multi-threaded quantum computing library written in C++11 and composed solely of header files. The library is not restricted to qubit systems or specific quantum information processing tasks, being capable of simulating arbitrary quantum processes. The main design factors taken in consideration were ease of use, portability, and performance.

Vlad Gheorghiu

2014-12-15T23:59:59.000Z

462

Quantum arithmetic with the Quantum Fourier Transform  

E-Print Network (OSTI)

The Quantum Fourier Transform offers an interesting way to perform arithmetic operations on a quantum computer. We review existing Quantum Fourier Transform adders and multipliers and propose some modifications that extend their capabilities. Among the new circuits, we propose a quantum method to compute the weighted average of a series of inputs in the transform domain.

Lidia Ruiz-Perez; Juan Carlos Garcia-Escartin

2014-11-21T23:59:59.000Z

463

Collapse of integer Hall gaps in a double-quantum-well system  

Science Journals Connector (OSTI)

For coupled double-quantum-well systems in which tunneling is important, the symmetric to antisymmetric energy gap leads to a quantum Hall effect. In this Letter we show that interaction effects in strong magnetic fields can destroy this gap, and present a theory which predicts the occurrence or nonoccurrence of a quantum Hall effect.

A. H. MacDonald; P. M. Platzman; G. S. Boebinger

1990-08-06T23:59:59.000Z

464

Quantum coherence and correlations in quantum system  

E-Print Network (OSTI)

Criteria of measure quantifying quantum coherence, a unique property of quantum system, are proposed recently. In this paper, we investigate the relative entropic measure of coherence. Based on its analytical expression, we give an operational interpretation of it with respect to the concept of quantum channel. On this basis, we derive the relation about the coherence and the coherent information in any quantum state. From the point of view of quantum measurement, we furthermore give three trade-offs among the coherence, discord-like and deficit-like quantum correlation quantities for any bipartite quantum state. As an application, we discuss the coherent property of the amplitude damping channel.

Zhengjun Xi; Yongming Li; Heng Fan

2014-08-14T23:59:59.000Z

465

Contextual completeness and a classification scheme for theories  

E-Print Network (OSTI)

We discuss the role of propositions, truth, context and observers in scientific theories. We introduce the concept of generalized proposition and use it to define an algorithm for the classification of any scientific theory. The algorithm assigns a number 0, 1, 2 or 3 to a given theory, thereby classifying it as of metaphysical, mathematical, classical or quantum class. The objective is to provide an impartial method of assessing the scientific status of any theory.

Jaroszkiewicz, George

2015-01-01T23:59:59.000Z

466

Orientifold points in M theory  

Science Journals Connector (OSTI)

We identify the lift to M theory of the four types of orientifold points, and show that they involve a chiral fermion on an orbifold fixed circle. From this lift, we compute the number of normalizable ground states for the SO(N) and Sp(N) supersymmetric quantum mechanics with sixteen supercharges. The results agree with known results obtained by the mass deformation method. The mass of the orientifold is identified with the Casimir energy.

Amihay Hanany; Barak Kol; Arvind Rajaraman

1999-01-01T23:59:59.000Z

467

On the "principle of the quantumness", the quantumness of Relativity, and the computational grand-unification  

E-Print Network (OSTI)

After reviewing recently suggested operational "principles of the quantumness", I address the problem on whether Quantum Theory (QT) and Special Relativity (SR) are unrelated theories, or instead, if the one implies the other. I show how SR can be indeed derived from causality of QT, within the computational paradigm "the universe is a huge quantum computer", reformulating QFT as a Quantum-Computational Field Theory (QCFT). In QCFT SR emerges from the fabric of the computational network, which also naturally embeds gauge invariance. In this scheme even the quantization rule and the Planck constant can in principle be derived as emergent from the underlying causal tapestry of space-time. In this way QT remains the only theory operating the huge computer of the universe. Is QCFT only a speculative tautology (theory as simulation of reality), or does it have a scientific value? The answer will come from Occam's razor, depending on the mathematical simplicity of QCFT. Here I will just start scratching the surface of QCFT, analyzing simple field theories, including Dirac's. The number of problems and unmotivated recipes that plague QFT strongly motivates us to undertake the QCFT project, since QCFT makes all such problems manifest, and forces a re-foundation of QFT.

Giacomo Mauro D'Ariano

2010-01-07T23:59:59.000Z

468

Quantum logic as superbraids of entangled qubit world lines  

E-Print Network (OSTI)

Presented is a topological representation of quantum logic that views entangled qubit spacetime histories (or qubit world lines) as a generalized braid, referred to as a superbraid. The crossing of world lines is purely quantum in nature, most conveniently expressed analytically with ladder-operator-based quantum gates. At a crossing, independent world lines can become entangled. Complicated superbraids are systematically reduced by recursively applying novel quantum skein relations. If the superbraid is closed (e.g. representing quantum circuits with closed-loop feedback, quantum lattice gas algorithms, loop or vacuum diagrams in quantum field theory), then one can decompose the resulting superlink into an entangled superposition of classical links. In turn, for each member link, one can compute a link invariant, e.g. the Jones polynomial. Thus, a superlink possesses a unique link invariant expressed as an entangled superposition of classical link invariants.

Jeffrey Yepez

2009-07-30T23:59:59.000Z

469

Quantum Apices: Identifying Limits of Entanglement, Nonlocality, & Contextuality  

E-Print Network (OSTI)

This work develops analytic methods to quantitatively demarcate quantum reality from its subset of classical phenomenon, as well as from the superset of general probabilistic theories. Regarding quantum nonlocality, we discuss how to determine the quantum limit of Bell-type linear inequalities. In contrast to semidefinite programming approaches, our method allows for the consideration of inequalities with abstract weights, by means of leveraging the Hermiticity of quantum states. Recognizing that classical correlations correspond to measurements made on separable states, we also introduce a practical method for obtaining sufficient separability criteria. We specifically vet the candidacy of driven and undriven superradiance as schema for entanglement generation. We conclude by reviewing current approaches to quantum contextuality, emphasizing the operational distinction between nonlocal and contextual quantum statistics. We utilize our abstractly-weighted linear quantum bounds to explicitly demonstrate a set of conditional probability distributions which are simultaneously compatible with quantum contextuality while being incompatible with quantum nonlocality. It is noted that this novel statistical regime implies an experimentally-testable target for the Consistent Histories theory of quantum gravity.

Elie Wolfe

2014-09-08T23:59:59.000Z

470

DFT+U Study of Polaronic Conduction in Li2O2 and Li2CO3: Implications for LiAir Batteries  

Science Journals Connector (OSTI)

DFT+U Study of Polaronic Conduction in Li2O2 and Li2CO3: Implications for LiAir Batteries ... The emission of greenhouse gases and the local pollution in the cities produced by the fossil fuel-powered vehicles (FFVs) is forcing the development of alternative power systems for automobiles. ... A delocalized solution was found. ...

J. M. Garcia-Lastra; J. S. G. Myrdal; R. Christensen; K. S. Thygesen; T. Vegge

2013-02-15T23:59:59.000Z

471

Entanglement Theory and the Second Law of Thermodynamics  

E-Print Network (OSTI)

Entanglement is central both to the foundations of quantum theory and, as a novel resource, to quantum information science. The theory of entanglement establishes basic laws, such as the non-increase of entanglement under local operations, that govern its manipulation and aims to draw from them formal analogies to the second law of thermodynamics. However, while in the second law the entropy uniquely determines whether a state is adiabatically accessible from another, the manipulation of entanglement under local operations exhibits a fundamental irreversibility which prevents the existence of such an order. Here we show that a reversible theory of entanglement and a rigorous relationship with thermodynamics may be established when one considers all non-entangling transformations. The role of the entropy in the second law is taken by the asymptotic relative entropy of entanglement in the basic law of entanglement. We show the usefulness of this new approach to general resource theories and to quantum information theory.

Fernando G. S. L. Brandao; Martin B. Plenio

2008-10-14T23:59:59.000Z

472

Hamilton-Jacobi-Bellman equations for Quantum Filtering and Control  

E-Print Network (OSTI)

We exploit the separation of the filtering and control aspects of quantum feedback control to consider the optimal control as a classical stochastic problem on the space of quantum states. We derive the corresponding Hamilton-Jacobi-Bellman equations using the elementary arguments of classical control theory and show that this is equivalent, in the Stratonovich calculus, to a stochastic Hamilton-Pontryagin setup. We show that, for cost functionals that are linear in the state, the theory yields the traditional Bellman equations treated so far in quantum feedback.

J. Gough; V. P. Belavkin; O. G. Smolyanov

2005-02-24T23:59:59.000Z

473

Quantum Thermometry  

E-Print Network (OSTI)

In this review article we revisit and spell out the details of previous work on how Berry phase can be used to construct a precision quantum thermometer. An important advantage of such a scheme is that there is no need for the thermometer to acquire thermal equilibrium with the sample. This reduces measurement times and avoids precision limitations. We also review how such methods can be used to detect the Unruh effect.

Robert B. Mann; Eduardo Martin-Martinez

2014-05-22T23:59:59.000Z

474

Serendipitous discoveries in nonlocal gravity theory  

Science Journals Connector (OSTI)

We present a class of generally covariant nonlocal gravity models which have a flat-space general relativistic limit and also possess a stable deSitter or anti-deSitter (AdS) background with an arbitrary value of its cosmological constant. The nonlocal action of the theory is formulated in the Euclidean signature spacetime and is understood as an approximation to the quantum effective action (generating functional of one-particle irreducible diagrams) originating from fundamental quantum gravity theory. Using the known relation between the Schwinger-Keldysh technique for quantum expectation values and the Euclidean quantum field theory we derive from this action the causal effective equations of motion for mean value of the metric field in the physical Lorentzian-signature spacetime. Thus we show that the (A)dS background of the theory carries as free propagating modes massless gravitons having two polarizations identical to those of the Einstein theory with a cosmological term. The on-shell action of the theory is vanishing both for the flat-space and (A)dS backgrounds which play the role of stable vacua underlying, respectively, the ultraviolet and infrared phases of the theory. We also obtain linearized gravitational potentials of compact matter sources and show that in the infrared (A)dS phase their effective gravitational coupling Geff can be essentially different from the Newton gravitational constant GN of the short-distance general relativistic phase. When Geff?GN the (A)dS phase can be regarded as a strongly coupled infrared modification of Einstein theory not only describing the dark energy mechanism of cosmic acceleration but also simulating the dark matter phenomenon by enhanced gravitational attraction at long distances.

A. O. Barvinsky

2012-05-09T23:59:59.000Z

475

Perturbation theory of von Neumann Entropy  

E-Print Network (OSTI)

In quantum information theory, von Neumann entropy plays an important role. The entropies can be obtained analytically only for a few states. In continuous variable system, even evaluating entropy numerically is not an easy task since the dimension is infinite. We develop the perturbation theory systematically for calculating von Neumann entropy of non-degenerate systems as well as degenerate systems. The result turns out to be a practical way of the expansion calculation of von Neumann entropy.

Xiao-yu Chen

2009-02-27T23:59:59.000Z

476

Wilson Loops and Area-Preserving Diffeomorphisms in Twisted Noncommutative Gauge Theory  

E-Print Network (OSTI)

We use twist deformation techniques to analyse the behaviour under area-preserving diffeomorphisms of quantum averages of Wilson loops in Yang-Mills theory on the noncommutative plane. We find that while the classical gauge theory is manifestly twist covariant, the holonomy operators break the quantum implementation of the twisted symmetry in the usual formal definition of the twisted quantum field theory. These results are deduced by analysing general criteria which guarantee twist invariance of noncommutative quantum field theories. From this a number of general results are also obtained, such as the twisted symplectic invariance of noncommutative scalar quantum field theories with polynomial interactions and the existence of a large class of holonomy operators with both twisted gauge covariance and twisted symplectic invariance.

Mauro Riccardi; Richard J. Szabo

2007-01-30T23:59:59.000Z

477

Wilson loops and area-preserving diffeomorphisms in twisted noncommutative gauge theory  

SciTech Connect

We use twist deformation techniques to analyze the behavior under area-preserving diffeomorphisms of quantum averages of Wilson loops in Yang-Mills theory on the noncommutative plane. We find that while the classical gauge theory is manifestly twist covariant, the holonomy operators break the quantum implementation of the twisted symmetry in the usual formal definition of the twisted quantum field theory. These results are deduced by analyzing general criteria which guarantee twist invariance of noncommutative quantum field theories. From this a number of general results are also obtained, such as the twisted symplectic invariance of noncommutative scalar quantum field theories with polynomial interactions and the existence of a large class of holonomy operators with both twisted gauge covariance and twisted symplectic invariance.

Riccardi, Mauro; Szabo, Richard J. [Department of Mathematics and Maxwell Institute for Mathematical Sciences, Heriot-Watt University, Colin Maclaurin Building, Riccarton, Edinburgh EH14 4AS (United Kingdom)

2007-06-15T23:59:59.000Z

478

Principles of Quantum Universe  

E-Print Network (OSTI)

The present monograph is devoted to the theory of gravitation derived consequently as joint nonlinear realization of conformal and affine symmetries by means of Cartan differential forms. In the framework of the joint nonlinear realization of conformal and affine symmetries the interpretation of the last cosmological observational data of Ia Supernovae, anisotropy of the primordial radiation temperature and the mass spectrum of electroweak bosons, including the Higgs particle mass in the expected region ~ 125 GeV, is given. All these observational and experimental data testify to the vacuum energy dominance. The vacuum Casimir energy is a source of intensive cosmological quantum creation gravitons and electroweak bosons including Higgs particles from the empty Universe during the first 10^(-12) sec. The products of decay of the electroweak bosons give the matter content of the present day Universe, including primordial radiation and its baryon asymmetry.

V. N. Pervushin; A. E. Pavlov

2014-02-03T23:59:59.000Z

479

Terahertz quantum cascade lasers  

Science Journals Connector (OSTI)

...Michael Pepper Terahertz quantum cascade lasers Jerome Faist 1 Lassaad Ajili...developments in terahertz quantum cascade lasers are reviewed. Structures...magnetic confinement| Terahertz quantum cascade lasers. | Recent developments in...

2004-01-01T23:59:59.000Z

480

Optical quantum memory  

E-Print Network (OSTI)

Quantum memory is important to quantum information processing in many ways: a synchronization device to match various processes within a quantum computer, an identity quantum gate that leaves any state unchanged, and a tool to convert heralded photons to photons-on-demand. In addition to quantum computing, quantum memory would be instrumental for the implementation of long-distance quantum communication using quantum repeaters. The importance of this basic quantum gate is exemplified by the multitude of optical quantum memory mechanisms being studied: optical delay lines, cavities, electromagnetically-induced transparency, photon-echo, and off-resonant Faraday interaction. Here we report on the state-of-the-art in the field of optical quantum memory, including criteria for successful quantum memory and current performance levels.

A. I. Lvovsky; B. C. Sanders; W. Tittel

2010-02-24T23:59:59.000Z

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


481

Path-integral solution of the one-dimensional Dirac quantum cellular automaton  

E-Print Network (OSTI)

Quantum cellular automata have been recently considered as a fundamental approach to quantum field theory, resorting to a precise automaton, linear in the field, for the Dirac equation in one dimension. In such linear case a quantum automaton is isomorphic to a quantum walk, and a convenient formulation can be given in terms of transition matrices, leading to a new kind of discrete path integral that we solve analytically in terms of Jacobi polynomials versus the arbitrary mass parameter.

Giacomo Mauro D'Ariano; Nicola Mosco; Paolo Perinotti; Alessandro Tosini

2014-06-04T23:59:59.000Z

482

Zeta Function Methods and Quantum Fluctuations  

E-Print Network (OSTI)

A review of some recent advances in zeta function techniques is given, in problem