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The exchange-correlation hole and potential of the homogeneous electron gas have been investigated within the random-phase approximation, employing the plasmon-pole approximation for the linear density response function. The angular…

Strongly Correlated Electrons · Physics 2023-04-12 K. Karlsson , F. Aryasetiawan

The random-phase approximation to the ground state correlation energy (RPA) in combination with exact exchange (EX) has brought Kohn-Sham (KS) density functional theory one step closer towards a universal, "general purpose first principles…

In this work we have calculated excitation energies and photoionization cross sections of Be and Ne in the exact-exchange (EXX) approximation of time-dependent density functional theory (TDDFT). The main focus has been on the frequency…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Maria Hellgren , Ulf von Barth

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 demonstrate that ground state energies approaching chemical accuracy can be obtained by combining the adiabatic connection fluctuation-dissipation theorem (ACFDT) with time-dependent density functional theory (TDDFT). The key ingredient…

Materials Science · Physics 2014-05-29 Thomas Olsen , Kristian S. Thygesen

Ensemble density functional theory (eDFT) is an exact time-independent alternative to time-dependent DFT (TD-DFT) for the calculation of excitation energies. Despite its formal simplicity and advantages in contrast to TD-DFT (multiple…

Strongly Correlated Electrons · Physics 2017-01-19 Killian Deur , Laurent Mazouin , Emmanuel Fromager

We express the high-frequency (anti-adiabatic) limit of the exchange-correlation kernels of an inhomogeneous electron gas in terms of the following equilibrium properties: the ground-state density, the kinetic stress tensor, the…

Strongly Correlated Electrons · Physics 2011-11-17 V. U. Nazarov , I. V. Tokatly , S. Pittalis , G. Vignale

Modern density functional theory (DFT) calculations employ the Kohn-Sham (KS) system of non-interacting electrons as a reference, with all complications buried in the exchange-correlation energy (Exc). The adiabatic connection formula gives…

Other Condensed Matter · Physics 2009-10-02 Zhenfei Liu , Kieron Burke

We review the theory and application of adiabatic exchange-correlation (xc-) kernels for ab initio calculations of ground state energies and quasiparticle excitations within the frameworks of the adiabatic connection fluctuation dissipation…

Using an end-to-end differentiable implementation of the Kohn-Sham self-consistent field equations, we obtain an accurate neural network-based exchange and correlation (XC) functional of the electronic density. The functional is optimized…

Chemical Physics · Physics 2021-06-09 Sebastian Dick , Marivi Fernandez-Serra

The performance of several common approximations for the exchange-correlation kernel within time-dependent density-functional theory is tested for elementary excitations in the homogeneous electron gas. Although the adiabatic local-density…

Materials Science · Physics 2007-05-23 Krzysztof Tatarczyk , Arno Schindlmayr , Matthias Scheffler

The homogeneous electron gas is one of the most studied model systems in condensed matter physics. It is also at the basis of the large majority of approximations to the functionals of density functional theory. As such, its…

Strongly Correlated Electrons · Physics 2020-07-14 Robert Schlesier , Carlos L. Benavides-Riveros , Miguel A. L. Marques

We present an exact expression for the frequency-dependent Kohn-Sham exact-exchange (EXX) kernel for periodic insulators, which can be employed for the calculation of electronic response properties within time-dependent (TD)…

Materials Science · Physics 2016-08-31 Yong-Hoon Kim , Andreas Goerling

The adiabatic connection fluctuation-dissipation theorem with the random phase approximation (RPA) has recently been applied with success to obtain correlation energies of a variety of chemical and solid state systems. The main merit of…

Materials Science · Physics 2015-03-20 Thomas Olsen , Kristian S. Thygesen

In recent work, generalized gradient approximations (GGA's) have been constructed from the energy density of the Airy gas for exchange but not for correlation. We report the random phase approximation (RPA) conventional correlation energy…

Materials Science · Physics 2009-06-30 Lucian A. Constantin , Adrienn Ruzsinszky , John P. Perdew

We present a new density-functional method of the self-consistent electronic-structure calculation which does not exploit any local density approximations (LDA). We use the exchange-correlation energy which consists of the exact exchange…

Statistical Mechanics · Physics 2009-10-30 Takao Kotani

With the aim of constructing an electronic structure approach that systematically goes beyond the GW and random phase approximation (RPA) we introduce a vertex correction based on the exact-exchange (EXX) potential of time-dependent density…

Materials Science · Physics 2018-07-16 Maria Hellgren , Nicola Colonna , Stefano de Gironcoli

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

An exchange-correlation energy functional $ E_{\mathrm xc} $ and the resultant exchange-correlation potential $ v_{\mathrm xc}({\bf r}) $ in density-functional theory are proposed using orbital-dependent coupling-constant-averaged pair…

Strongly Correlated Electrons · Physics 2007-05-23 Hiroshi Yasuhara , Masahiko Higuchi , Yoshiyuki Kawazoe

According to time-dependent density functional theory, the exact exchange-correlation kernel f$_{xc}$(n, q, $\omega$) determines not only the ground-state energy but also the excited-state energies/lifetimes and time-dependent linear…

Chemical Physics · Physics 2020-07-01 Adrienn Ruzsinszky , Niraj K. Nepal , J. M. Pitarke , John P. Perdew