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An exchange correlation energy functional involving fractional power of the one-body reduced density matrix [Phys. Rev. B {\bf 78}, 201103 (2008)] is applied to finite systems and to the homogeneous electron gas. The performance of the…

Strongly Correlated Electrons · Physics 2015-05-13 N. N. Lathiotakis , S. Sharma , J. K. Dewhurst , F. Eich , M. A. L. Marques , E. K. U. Gross

Conditional-probability density functional theory (CP-DFT) is a formally exact method for finding correlation energies from Kohn-Sham DFT without evaluating an explicit energy functional. We present details on how to generate accurate…

Chemical Physics · Physics 2022-05-04 Dennis Perchak , Ryan J. McCarty , Kieron Burke

Using the methodology of conditional-probability density functional theory, and several mild assumptions, we calculate the temperature-dependence of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). This…

Chemical Physics · Physics 2023-08-17 John Kozlowski , Dennis Perchak , Kieron Burke

A two-orbital two-electron diatomic model resembling LiH is used to investigate the differences between the exact L\"owdin-Shull and approximate Hartree-Fock-Bogoliubov and Baerends-Buijse density matrix functionals in the medium- to…

Chemical Physics · Physics 2020-09-09 Robert van Meer , Jeng-Da Chai

We introduce a novel non-local ingredient for the construction of exchange density functionals: the reduced Hartree parameter, which is invariant under the uniform scaling of the density and represents the exact exchange enhancement factor…

Other Condensed Matter · Physics 2016-09-04 L. A. Constantin , E. Fabiano , F. Della Sala

We assess the performance of recent density functionals for the exchange-correlation energy of a nonmolecular solid, by applying accurate calculations with the GAUSSIAN, BAND, and VASP codes to a test set of 24 solid metals and non-metals.…

Realizing the potential for predictive density functional calculations of matter under extreme conditions depends crucially upon having an exchange-correlation (XC) free energy functional accurate over a wide range of state conditions.…

Materials Science · Physics 2018-02-21 Valentin V. Karasiev , James W. Dufty , S. B. Trickey

Analytic mathematical models for the static spin ($G_-$) and density ($G_+$) local field factors for the uniform electron gas (UEG) as functions of wavevector and density are presented. These models closely fit recent quantum Monte Carlo…

Strongly Correlated Electrons · Physics 2023-06-14 Aaron D. Kaplan , Carl A. Kukkonen

We consider dynamical correlation functions of short range interacting electrons in one dimension at finite temperature. Below a critical value of the chemical potential there is no Fermi surface anymore, and the system can no longer be…

Strongly Correlated Electrons · Physics 2009-10-31 F. Göhmann , V. E. Korepin

We compare the behavior of the finite-temperature Hartree-Fock model with that of thermal density functional theory using both ground-state and temperature-dependent approximate exchange functionals. The test system is bcc Li in the…

Materials Science · Physics 2013-11-26 Valentin V. Karasiev , Travis Sjostrom , S. B. Trickey

We revisit the Hartree-Fock (HF) calculation for the uniform electron gas, or jellium model, whose predictions -- divergent derivative of the energy dispersion relation and vanishing density of states (DOS) at the Fermi level -- are in…

Strongly Correlated Electrons · Physics 2015-03-02 Alexander I. Blair , Aristeidis Kroukis , Nikitas I. Gidopoulos

Building on the discussion in PRA 93, 042510 (2016), we present a systematic derivation of gradient corrections to the kinetic-energy functional and the one-particle density, in particular for two-dimensional systems. We derive the leading…

Quantum Gases · Physics 2017-09-08 Martin-Isbjörn Trappe , Yink Loong Len , Hui Khoon Ng , Berthold-Georg Englert

The key feature of nonlocal kinetic energy functionals is their ability to reduce to the Thomas-Fermi functional in the regions of high density and to the von Weizs\"acker functional in the region of low density/high density gradient. This…

Materials Science · Physics 2021-03-31 Xuecheng Shao , Wenhui Mi , Michele Pavanello

We explore the simplification of widely used meta-generalized-gradient approximation (mGGA) exchange-correlation functionals to the Laplacian level of refinement by use of approximate kinetic energy density functionals (KEDFs). Such…

Chemical Physics · Physics 2017-12-01 Daniel Mejia-Rodriguez , S. B. Trickey

Density functional calculations on atoms are often used for determining accurate initial guesses as well as generating various types of pseudopotential approximations and efficient atomic-orbital basis sets for polyatomic calculations. To…

Computational Physics · Physics 2023-10-30 Susi Lehtola

We derive an exact representation of the exchange-correlation energy within density functional theory (DFT) which spawns a class of approximations leading to correct long-range asymptotic behavior. In what amounts to be the simplest…

Materials Science · Physics 2009-11-10 Roi Baer , Daniel Neuhauser

Physically valid and numerically efficient approximations for the exchange and correlation energy are critical for reduced density-matrix functional theory to become a widely used method in electronic structure calculations. Here we examine…

Strongly Correlated Electrons · Physics 2016-03-23 A. Putaja , F. G. Eich , T. Baldsiefen , E. Rasanen

We calculate the correlation energy of a two-dimensional homogeneous electron gas using several available approximations for the exchange-correlation kernel $f_{\rm xc}(q,\omega)$ entering the linear dielectric response of the system. As in…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 R. Asgari , M. Polini , B. Davoudi , M. P. Tosi

In a recent paper [Phys. Rev. B 90, 115134 (2014)] we put forward a diagrammatic expansion for the self-energy which guarantees the positivity of the spectral function. In this work we extend the theory to the density response function. We…

Other Condensed Matter · Physics 2015-06-24 A. -M. Uimonen , G. Stefanucci , Y. Pavlyukh , R. van Leeuwen

We consider the cumulant expansion of the PAM employing the hybridization as perturbation (Phys. Rev. B 50, 17933 (1994)), and we obtain formally exact one-electron Green's functions (GF). These GF contain effective cumulants that are as…

Strongly Correlated Electrons · Physics 2010-07-13 M. E. Foglio , T. Lobo , M. S. Figueira