Van der Waals Density Functional for General Geometries

TL;DR

This paper introduces a practical density functional theory scheme that seamlessly incorporates van der Waals forces for general geometries, improving the accuracy of modeling nonlocal correlations in molecular systems.

Contribution

It develops a new van der Waals density functional that generalizes previous methods to arbitrary geometries using a simple, parametrized kernel based on local density and gradient.

Findings

Accurately describes rare gas and benzene dimers.

Provides a realistic account of nonlocal correlation effects.

Offers a practical approach for including van der Waals forces in DFT calculations.

Abstract

A scheme within density functional theory is proposed that provides a practical way to generalize to unrestricted geometries the method applied with some success to layered geometries [H. Rydberg, et al., Phys. Rev. Lett. 91, 126402 (2003)]. It includes van der Waals forces in a seamless fashion. By expansion to second order in a carefully chosen quantity contained in the long range part of the correlation functional, the nonlocal correlations are expressed in terms of a density-density interaction formula. It contains a relatively simple parametrized kernel, with parameters determined by the local density and its gradient. The proposed functional is applied to rare gas and benzene dimers, where it is shown to give a realistic description.