PNNL

Abstract

Interaction analysis techniques, including the many-body expansion (MBE), symmetry-adapted perturbation theory (SAPT) and energy decomposition analysis (EDA), allow for an intuitive understanding of complex molecular interactions. We review these methods by first providing a historical context for the study of many-body interactions and discussing how non-additivities emerge from Hamiltonians containing strictly pairwise additive interactions. We elaborate on the synergy between these interaction analysis techniques and the development of advanced force fields aimed at accurately reproducing the Born-Oppenheimer potential energy surface. In particular, we focus on ab initio based force fields that aim to explicitly reproduce many-body terms and are fitted to high level electronic structure results. These force fields generally incorporate many-body effects through (i) parameterization of distributed multipoles, (ii) explicit fitting of the MBE, (iii) inclusion of many-atom features in a neural network, and (iv) coarse-graining of many-body terms into an effective two-body term. We also discuss some emerging uses of the MBE which aim to improve both the accuracy and speed of ab initio molecular dynamics.