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A curious behavior of electron correlation energy is explored. Namely, the correlation energy is the energy that tends to drive the system toward that of the uniform electron gas. As such, the energy assumes its maximum value when a…

Materials Science · Physics 2019-12-17 Teepanis Chachiyo , Hathaithip Chachiyo

We consider density functionals for exchange and correlation energies in two-dimensional systems. The functionals are constructed by making use of exact constraints for the angular averages of the corresponding exchange and correlation…

Strongly Correlated Electrons · Physics 2010-02-25 E. Rasanen , S. Pittalis

We investigate the adiabatic approximation to the exact-exchange kernel for calculating correlation energies within the adiabatic-connection fluctuation-dissipation framework of time-dependent density functional theory. A numerical study is…

Chemical Physics · Physics 2023-05-12 Maria Hellgren , Lucas Baguet

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 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

The correlation energy of the homogeneous electron gas is evaluated by solving the Bethe-Salpeter equation (BSE) beyond the Tamm-Dancoff approximation for the electronic polarisation propagator. The BSE is expected to improve upon the…

Materials Science · Physics 2016-06-15 Emanuele Maggio , Georg Kresse

A simple approximate expression in real and reciprocal spaces is given for the static exchange-correlation kernel of a uniform electron gas interacting with the long-range part only of the Coulomb interaction. This expression interpolates…

Materials Science · Physics 2009-11-11 Julien Toulouse

Methods for estimating the correlation energy of molecules and other electronic systems are discussed based on the assumption that the correlation energy can be partitioned between atomic regions. In one method, the electron density is…

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

The energy-energy correlation function of the two-dimensional Ising model with weakly fluctuating random bonds is evaluated in the large scale limit. Two correlation lengths exist in contrast to one correlation length in the pure 2D Ising…

Condensed Matter · Physics 2007-05-23 K. Ziegler

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

The dynamical, long-wavelength longitudinal and transverse exchange-correlation potentials for a homogeneous electron gas are evaluated in a microscopic model based on an approximate decoupling of the equation of motion for the…

Condensed Matter · Physics 2009-10-30 S. Conti , R. Nifosi' , M P Tosi

The role of the exchange-correlation potential and the exchange-correlation kernel in the calculation of excitation energues from time-dependent density functional theory is studied. Excitation energies of the He and Be atoms are…

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

In this paper we analyze how radiation effects influence the correlation functions, the excess energy, and in turn the electron correlation energy of the quantized electron gas at temperature $T=0$. To that aim we resort to a statistical…

Statistical Mechanics · Physics 2020-08-26 Johan S. Høye , Enrique Lomba

The subject of this study is the exchange-correlation-energy functional of reduced density matrix functional theory. Approximations of this functional are tested by applying them to the homogeneous electron gas. We find that two…

Materials Science · Physics 2011-01-14 N. N. Lathiotakis , N. Helbig , E. K. U. Gross

We show that the expression of the high-density (i.e small-$r_s$) correlation energy per electron for the one-dimensional uniform electron gas can be obtained by conventional perturbation theory and is of the form $\Ec(r_s) = -\pi^2/360 +…

Strongly Correlated Electrons · Physics 2013-08-19 Pierre-François Loos

The variational and diffusion quantum Monte Carlo methods are used to calculate the correlation energy of the paramagnetic three-dimensional homogeneous electron gas at intermediate to high density. Ground state energies in finite cells are…

Strongly Correlated Electrons · Physics 2023-03-29 Sam Azadi , N. D. Drummond , S. M. Vinko

We introduce a new paradigm for finite and infinite strict-one-dimensional uniform electron gases. In this model, $n$ electrons are confined to a ring and interact via a bare Coulomb operator. In the high-density limit (small-$r_s$, where…

Strongly Correlated Electrons · Physics 2012-08-15 Pierre-François Loos , Peter M. W. Gill

The three-dimensional electron-gas model has been a major focus for many-body theory applied to the electronic properties of metals and semiconductors. Because the model neglects band effects, whereas electronic systems are generally more…

Strongly Correlated Electrons · Physics 2015-06-25 A. H. MacDonald

We present a practical and accurate density functional for the exchange-correlation energy of electrons in two dimensions. The exchange part is based on a recent two-dimensional generalized-gradient approximation derived by considering the…

Strongly Correlated Electrons · Physics 2010-06-30 E. Rasanen , S. Pittalis , J. G. Vilhena , M. A. L. Marques

We fit finite-temperature path integral Monte Carlo calculations of the exchange-correlation energy of the 3D finite-temperature homogeneous electron gas in the warm-dense regime (r_{s} = (3/4\pi n)^{1/3} a_{B}^{-1} < 40 and \Theta =…

Strongly Correlated Electrons · Physics 2014-09-11 Ethan W. Brown , Jonathan L. DuBois , Markus Holzmann , David M. Ceperley