Efficient, long-range correlation from occupied wavefunctions only

TL;DR

This paper introduces an efficient exchange-correlation functional based on continuum mechanics and RPA that accurately predicts binding energies and van der Waals forces in metal slabs, outperforming traditional methods.

Contribution

It develops a novel, computationally efficient functional that captures long-range correlations and vdW interactions more accurately than existing local density approximations.

Findings

Better agreement with full dRPA calculations for metal slab binding energies.

Correctly reproduces the non-retarded vdW power law at large distances.

Achieves improved accuracy over traditional local density approximations.

Abstract

We use continuum mechanics [Tao \emph{et al}, PRL{\bf 103},086401] to approximate the dynamic density response of interacting many-electron systems. Thence we develop a numerically efficient exchange-correlation energy functional based on the Random Phase Approximation (dRPA). The resulting binding energy curve $E(D)$ for thin parallel metal slabs at separation $D$ better agrees with full dRPA calculations than does the Local Density Approximation. We also reproduce the correct non-retarded van der Waals (vdW) power law $E(D)\aeq -C_{5/2}D^{-5/2}$ as $D\to\infty$, unlike most vdW functionals.