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Semi-local density functionals for the exchange-correlation energy of electrons are extensively used as it produce realistic and accurate results for finite and extended systems. The choice of techniques play crucial role in constructing…

Materials Science · Physics 2017-11-01 Subrata Jana , Prasanjit Samal

Exact density functionals for the exchange and correlation energies are approximated in practical calculations for the ground-state electronic structure of a many-electron system. An important exact constraint for the construction of…

Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize, thereby reducing the magnitude of the interaction. Exchange integrals of…

Chemical Physics · Physics 2022-05-16 Jerry L. Whitten

We train a neural network as the universal exchange-correlation functional of density-functional theory that simultaneously reproduces both the exact exchange-correlation energy and potential. This functional is extremely non-local, but…

Computational Physics · Physics 2019-10-10 Jonathan Schmidt , Carlos L. Benavides-Riveros , Miguel A. L. Marques

We use variational quantum Monte Carlo to calculate the density-functional exchange-correlation hole n_{xc}, the exchange-correlation energy density e_{xc}, and the total exchange-correlation energy E_{xc}, of several electron gas systems…

Materials Science · Physics 2009-10-31 Maziar Nekovee , W. M. C. Foulkes , R. J. Needs

A review of the approximations in any time-dependent density functional calculation of excitation energies is given. The single-pole approximation for the susceptibility is used to understand errors in popular approximations for the…

Materials Science · Physics 2007-05-23 Kieron Burke , Martin Petersilka , E. K. U. Gross

While in principle exact, Kohn-Sham density functional theory -- the workhorse of computational chemistry -- must rely on approximations for the exchange-correlation functional. Despite staggering successes, present-day approximations still…

The derivative discontinuity of the exchange-correlation functional of density-functional theory is cast as the difference of two types of electron affinities. We show that standard Kohn-Sham calculations can be used to calculate both…

Chemical Physics · Physics 2007-12-13 F. P. Rosselli , A. B. F. da Silva , K. Capelle

We discuss energy densities in the strong-interaction limit of density functional theory, deriving an exact expression within the definition (gauge) of the electrostatic potential of the exchange-correlation hole. Exact results for small…

Chemical Physics · Physics 2012-11-14 André Mirtschink , Michael Seidl , Paola Gori-Giorgi

We consider electronic exchange and correlation effects in density-functional calculations of two-dimensional systems. Starting from wave function calculations of total energies and electron densities of inhomogeneous model systems, we…

Mesoscale and Nanoscale Physics · Physics 2012-05-30 Ilja Makkonen , Mikko M. Ervasti , Ville Kauppila , Ari Harju

Using an accurate semi-analytic wavefunction for two electron atoms, we construct the external potential for varying strength of electron-electron (e-e) interaction. Using this potential we explicitly calculate the energy of their positive…

Atomic and Molecular Clusters · Physics 2016-02-18 Rabeet Singh Chauhan , Manoj K. Harbola

Static correlation error(SCE) inevitably emerges when a dissociation of a covalent bond is described with a conventional denstiy-functional theory (DFT) for electrons. SCE gives rise to a serious overshoot in the potential energy at the…

Computational Physics · Physics 2020-08-10 Hideaki Takahashi

The capability of density-functional theory to deal with the ground-state of strongly correlated low-dimensional systems, such as semiconductor quantum dots, depends on the accuracy of functionals developed for the exchange and correlation…

Strongly Correlated Electrons · Physics 2009-02-25 S. Pittalis , E. Rasanen , C. Proetto , E. K. U. Gross

We propose a new approach to approximate the exchange and correlation (XC) functional in density functional theory. The XC potential is considered as an electrostatic potential, generated by a fictitious XC density, which is in turn a…

Chemical Physics · Physics 2013-05-29 Xavier Andrade , Alán Aspuru-Guzik

By exploiting freedoms in the definitions of 'correlation', 'exchange' and 'Hartree' physics in ensemble systems we better generalise the notion of 'exact exchange' (EXX) to systems with fractional occupations functions of the frontier…

Atomic Physics · Physics 2014-07-28 Tim Gould , John F. Dobson

We describe a method for calculating the exchange and correlation (XC) contributions to the total energy, effective potential, and stress tensor in the generalized gradient approximation. We avoid using the analytical expressions for the…

Materials Science · Physics 2009-11-07 L. C. Balbas , Jose Luis Martins , Jose M. Soler

We derive an approximate local density functional for the exchange-correlation energy to be used in density-functional calculations of two-dimensional systems. In the derivation we employ the Colle-Salvetti wave function within the scheme…

Strongly Correlated Electrons · Physics 2010-07-12 S. Sakiroglu , E. Rasanen

The strong-coupling perturbation theory (SCPT) for correlated electron systems is extended to the case of full Coulomb interaction. The Coulomb mechanism of the orbital polarization is discussed and attention is paid to the importance of…

Strongly Correlated Electrons · Physics 2007-05-23 I. Sandalov , U. Lundin , O. Eriksson

We present a controlled method for computing the exchange coupling in correlated one-dimensional electron systems based on the relation between the exchange constant and the pair-correlation function of spinless electrons. This relation is…

Strongly Correlated Electrons · Physics 2007-05-23 Michael M. Fogler , Eugene Pivovarov

The time-dependent exchange-correlation potential has an unusual task in directing fictitious non-interacting electrons to move with exactly the same probability density as true interacting electrons. This has intriguing implications for…

Chemical Physics · Physics 2024-06-19 Davood Dar , Lionel Lacombe , Neepa T. Maitra