Nonlocal van der Waals density functional: The simpler the better

TL;DR

This paper introduces a simplified nonlocal correlation functional for density functional theory that accurately models dispersion interactions, is easy to implement, and performs well across various weakly-bound systems.

Contribution

A new, simpler nonlocal correlation functional that accurately captures dispersion interactions using only electron density, with efficient self-consistent implementation.

Findings

Accurately predicts interaction energies of weakly-bound complexes

Provides precise equilibrium intermonomer separations

Yields reliable covalent bond lengths and atomization energies

Abstract

We devise a nonlocal correlation energy functional that describes the entire range of dispersion interactions in a seamless fashion using only the electron density as input. The new functional is considerably simpler than its predecessors of a similar type. The functional has a tractable and robust analytic form that lends itself to efficient self-consistent implementation. When paired with an appropriate exchange functional, our nonlocal correlation model yields accurate interaction energies of weakly-bound complexes, not only near the energy minima but also far from equilibrium. Our model exhibits an outstanding precision at predicting equilibrium intermonomer separations in van der Waals complexes. It also gives accurate covalent bond lengths and atomization energies. Hence the functional proposed in this work is a computationally inexpensive electronic structure tool of broad applicability.