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In this chapter, we provide a review of ground-state Kohn-Sham density-functional theory of electronic systems and some of its extensions, we present exact expressions and constraints for the exchange and correlation density functionals,…

Chemical Physics · Physics 2022-09-12 Julien Toulouse

The conventional approaches to the inverse density functional theory problem typically assume non-degeneracy of the Kohn-Sham (KS) eigenvalues, greatly hindering their use in open-shell systems. We present a generalization of the inverse…

Chemical Physics · Physics 2024-01-09 Bikash Kanungo , Jeffrey Hatch , Paul M. Zimmerman , Vikram Gavini

Accurately describing excited states within Kohn-Sham (KS) density functional theory (DFT), particularly those which induce ionization and charge transfer, remains a great challenge. Common exchange-correlation (xc) approximations are…

Materials Science · Physics 2021-02-09 Eli Kraisler , M. J. P. Hodgson , E. K. U. Gross

The reliability of density-functional calculations hinges on accurately approximating the unknown exchange-correlation (xc) potential. Common (semi-)local xc approximations lack the jump experienced by the exact xc potential as the number…

Atomic Physics · Physics 2021-01-15 M. J. P. Hodgson , E. Kraisler , E. K. U. Gross

We consider the extended Hubbard model and introduce a corresponding Heisenberg-like problem written in terms of spin operators. The derived formalism is reminiscent of Anderson's idea of the effective exchange interaction and takes into…

Strongly Correlated Electrons · Physics 2018-07-25 E. A. Stepanov , S. Brener , F. Krien , M. Harland , A. I. Lichtenstein , M. I. Katsnelson

We present the current-density functional theory for the superconductor immersed in the magnetic field. The order parameter of the superconducting state, transverse component of the paramagnetic current-density, and electron density are…

Superconductivity · Physics 2016-10-04 Katsuhiko Higuchi , Masahiko Higuchi

A description of non-collinear magnetism in the framework of spin-density functional theory is presented for the exact exchange energy functional which depends explicitly on two-component spinor orbitals. The equations for the effective…

The polarization-dependence of the exchange-correlation (XC) energy functional of periodic insulators within Kohn-Sham (KS) density-functional theory requires a ${\cal O} (1/q^2)$ divergence in the XC kernel for small vectors q. This…

Materials Science · Physics 2009-10-30 Ph. Ghosez , X. Gonze , R. W. Godby

Based on exact limits and quantum Monte Carlo simulations, we obtain, at any density and spin polarization, an accurate estimate for the energy of a modified homogeneous electron gas where electrons repel each other only with a long-range…

Materials Science · Physics 2009-11-11 Simone Paziani , Saverio Moroni , Paola Gori-Giorgi , Giovanni B. Bachelet

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

The frequency-dependent exchange-correlation potential, which appears in the usual Kohn-Sham formulation of a time-dependent linear response problem, is a strongly nonlocal functional of the density, so that a consistent local density…

Condensed Matter · Physics 2009-10-28 G. Vignale , Walter Kohn

Kohn-Sham (KS) density functional theory (DFT) is a very efficient method for calculating various properties of solids as, for instance, the total energy, the electron density, or the electronic band structure. The KS-DFT method leads to…

Materials Science · Physics 2019-09-20 Fabien Tran , Jan Doumont , Leila Kalantari , Ahmad W. Huran , Miguel A. L. Marques , Peter Blaha

The dissociation of molecules, even the most simple hydrogen molecule, cannot be described accurately within density functional theory because none of the currently available functionals accounts for strong on-site correlation. This problem…

Strongly Correlated Electrons · Physics 2011-01-14 N. Helbig , I. V. Tokatly , A. Rubio

Popular approximations to the exchange-correlation (xc) energy of density functional theory do not yield the spatial `step' structures in the exact xc potential which are necessary to describe dissociation and electron excitation with the…

Materials Science · Physics 2021-09-08 M. J. P. Hodgson

We study the competition between the exchange and the direct Coulomb interaction near the edge of a two-dimensional electron gas in a strong magnetic field using density-functional theory in a local approximation for the exchange-energy…

Condensed Matter · Physics 2009-10-28 T. H. Stoof , Gerrit E. W. Bauer

A method for calculating the Kohn--Sham exchange-correlation potential, $v_\text{XC}(\mathbf{r})$, from a given electronic wavefunction is devised and implemented. It requires on input one- and two-electron density matrices and involves…

Chemical Physics · Physics 2015-08-19 Ilya G. Ryabinkin , Sviataslau V. Kohut , Viktor N. Staroverov

We identify the key property that the exchange-correlation (XC) kernel of time-dependent density functional theory must have in order to describe long-range charge-transfer excitations. We show that the discontinuity of the XC potential as…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 M. Hellgren , E. K. U. Gross

It has been known for some time that the exchange-correlation potential in time-dependent density functional theory is an intrinsically nonlocal functional of the density as soon as one goes beyond the adiabatic approximation. In this paper…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Z. Qian , A. Constantinescu , G. Vignale

An efficient method to compute magnetic exchange interactions in systems with strong correlations is introduced. It is based on a magnetic force theorem which evaluates linear response due to rotations of magnetic moments and uses a novel…

Strongly Correlated Electrons · Physics 2007-05-23 Xiangang Wan , Quan Yin , Sergej Y. Savrasov

We propose approximations which go beyond the local density approximation for the short-range exchange and correlation density functionals appearing in a multi-determinantal extension of the Kohn-Sham scheme. A first approximation consists…

Chemical Physics · Physics 2009-11-10 Julien Toulouse , Francois Colonna , Andreas Savin