A Transferable Model of Molecular Exchange-Repulsion Interaction from Anisotropic Valence Density Overlap

TL;DR

This paper introduces the AVDO model for exchange-repulsion that achieves high accuracy with only two universal parameters, demonstrating transferability across many chemical systems and promising integration with machine learning force fields.

Contribution

The AVDO model simplifies exchange-repulsion modeling with universal parameters, enabling accurate, transferable force fields for diverse molecules.

Findings

Achieves sub-kcal/mol accuracy for organic dimers

Contains only two universal parameters transferable across multiple elements

Validated on 1,872 molecular pairs and condensed-phase trajectories

Abstract

Pauli exchange-repulsion is the dominant short-range intermolecular interaction and it is an essential component of molecular force fields. Current approaches to modeling Pauli repulsion in molecular force fields often rely on over 20 atom types to achieve chemical accuracy. The number of parameters in these approaches hampers the development of force fields with quantum-chemical accuracy that are transferable across many chemical systems. We present the anisotropic valence density overlap (AVDO) model for exchange-repulsion. The model produces sub-kcal/mol accuracy for dimers of organic molecules and contains two universal parameters, which we demonstrate are transferable for molecules composed of H, C, N, O, F, P, S, Cl, and Br. The model is tested on 1,872 unique molecular pairs selected from a set of 135 molecules, and samples dissociation curves and configurations from condensed-phase molecular dynamics trajectories. Given recent progress in machine learning of the electronic density, this model offers a promising path toward high-accuracy, next-generation machine-learned force fields.