Coarse-grained conformational surface hopping: Methodology and transferability

TL;DR

This paper introduces a coarse-grained conformational surface hopping method that improves molecular dynamics simulations by coupling conformational states, extends it to non-bonded interactions, and demonstrates transferability across different systems and conditions.

Contribution

It presents a detailed methodology for CG surface hopping, extends it to non-bonded interactions, and explores its transferability across various thermodynamic states and chemical compositions.

Findings

Significant improvement in approximating many-body potential of mean force.

Good agreement with atomistic calculations across different conditions.

Identification of a weak-transferability regime for force fields.

Abstract

Coarse-grained (CG) conformational surface hopping (SH) adapts the concept of multisurface dynamics, initially developed to describe electronic transitions in chemical reactions, to accurately describe classical molecular dynamics at a reduced level. The SH scheme couples distinct conformational basins (states), each described by its own force field (surface), resulting in a significant improvement of the approximation to the many-body potential of mean force [Phys. Rev. Lett. 121, 256002 (2018)]. The present study first describes CG SH in more detail, through both a toy model and a three-bead model of hexane. We further extend the methodology to non-bonded interactions and report its impact on liquid properties. Finally, we investigate the transferability of the surfaces to distinct systems and thermodynamic state points, through a simple tuning of the state probabilities. In particular, applications to variations in temperature and chemical composition show good agreement with reference atomistic calculations, introducing a promising "weak-transferability regime," where CG force fields can be shared across thermodynamic and chemical neighborhoods.