ISA-Pol: Distributed polarizabilities and dispersion models from a basis-space implementation of the iterated stockholder atoms procedure

TL;DR

This paper introduces ISA-Pol, a new basis-space method for calculating distributed polarizabilities and dispersion models in molecules, which are accurate, basis-set limit convergent, and responsive to chemical changes.

Contribution

The paper presents ISA-Pol, a novel approach combining BS-ISA with localization to produce non-local, frequency-dependent polarizabilities and dispersion models with desirable physical properties.

Findings

Models have a well-defined basis-set limit.

Dispersion energies are highly accurate.

Models satisfy common combination rules.

Abstract

Recently we have developed a robust, basis-space implementation of the iterated stockholder atoms (BS-ISA) approach for defining atoms in a molecule. This approach has been shown to yield rapidly convergent distributed multipole expansions with a well-defined basis-set limit. Here we use this method as the basis of a new approach, termed ISA-Pol, for obtaining non-local distributed frequency-dependent polarizabilities. We demonstrate how ISA-Pol can be combined with localization methods to obtain distributed dispersion models that share the many unique properties of the ISA: These models have a well-defined basis-set limit, lead to very accurate dispersion energies, and, remarkably, satisfy commonly used combination rules to a good accuracy. As these models are based on the ISA, they can be expected to respond to chemical and physical changes naturally, and thus they may serve as the basis for the next generation of polarization and dispersion models for ab initio force-field development.