Efficient, long-range correlation from occupied wave functions only

Abstract

Via continuum mechanics [J. Tao, X. Gao, G. Vignale, and I. V. Tokatly, Phys. Rev. Lett. 103, 086401 (2009)] with direct random phase approximation (dRPA) screening, we develop a numerically efficient general-geometry electronic exchange-correlation energy functional. It gives correct asymptotic power laws for dispersion interactions between insulators or metals. As a numerical example we obtain the full binding energy curves $\overline{\ensuremath{\epsilon}}(D)$ for parallel metal slabs of small but finite thickness: At all separations $D$ our $\overline{\ensuremath{\epsilon}}(D)$ agrees better with full dRPA correlation calculations than does the local density approximation, while being much more efficient than full dRPA correlation.