Dispersion interactions from a local polarizability model

TL;DR

This paper introduces a local polarizability model to accurately compute dispersion interactions, improving the physical justification and agreement with benchmark values for atoms and molecules.

Contribution

It presents a new local approximation for dynamic polarizability that enhances the calculation of dispersion energies in a physically justified way.

Findings

Accurate C_6 coefficients for various atoms and molecules

Good agreement with benchmark dispersion energies

Analysis of local polarizability approximations

Abstract

A local approximation for dynamic polarizability leads to a nonlocal functional for the long-range dispersion interaction energy via an imaginary-frequency integral. We analyze several local polarizability approximations and argue that the form underlying the construction of our recent van der Waals functional [O. A. Vydrov and T. Van Voorhis, Phys. Rev. Lett. 103, 063004 (2009)] is particularly well physically justified. Using this improved formula, we compute dynamic dipole polarizabilities and van der Waals C_6 coefficients for a set of atoms and molecules. Good agreement with the benchmark values is obtained in most cases.