Linear density response function within the time-dependent exact-exchange approximation

TL;DR

This paper computes the frequency-dependent exact exchange kernel within time-dependent density functional theory using cubic splines, enabling accurate calculations of response functions, polarizabilities, van der Waals coefficients, and correlation energies for spherical atoms.

Contribution

It introduces a computational method based on cubic splines to calculate the TDEXX kernel, improving the accuracy of response properties in spherical atoms.

Findings

TDEXX results closely match TD Hartree-Fock.

Correlation energies are highly accurate.

Static polarizabilities and van der Waals coefficients are reliably computed.

Abstract

We have calculated the frequency-dependent exact exchange (EXX) kernel of time-dependent (TD) density functional theory employing our recently proposed computational method based on cubic splines. With this kernel we have calculated the linear density response function and obtained static polarizabilites, van der Waals coefficients and correlation energies for all spherical spin compensated atoms up to Argon. Some discrete excitation energies have also been calculated for Be and Ne. As might be expected, the results of the TDEXX approximation are close to those of TD Hartree-Fock theory. In addition, correlation energies obtained by integrating over the strength of the Coulomb interaction turn out to be highly accurate.