# Coarse-Graining Auto-Encoders for Molecular Dynamics

## TL;DR

Autograin introduces an auto-encoder-based framework that simultaneously learns optimal coarse-grained mappings and potential functions, significantly advancing molecular dynamics simulations by reducing computational costs while maintaining accuracy.

## Contribution

The paper presents a novel auto-encoder approach for automatic, joint learning of coarse-grained representations and potentials in molecular dynamics.

## Key findings

- Successfully applied to single-molecule systems
- Effective in bulk-phase periodic simulations
- Reduces computational cost while preserving accuracy

## Abstract

Molecular dynamics simulations provide theoretical insight into the microscopic behavior of materials in condensed phase and, as a predictive tool, enable computational design of new compounds. However, because of the large temporal and spatial scales involved in thermodynamic and kinetic phenomena in materials, atomistic simulations are often computationally unfeasible. Coarse-graining methods allow simulating larger systems, by reducing the dimensionality of the simulation, and propagating longer timesteps, by averaging out fast motions. Coarse-graining involves two coupled learning problems; defining the mapping from an all-atom to a reduced representation, and the parametrization of a Hamiltonian over coarse-grained coordinates. Multiple statistical mechanics approaches have addressed the latter, but the former is generally a hand-tuned process based on chemical intuition. Here we present Autograin, an optimization framework based on auto-encoders to learn both tasks simultaneously. Autograin is trained to learn the optimal mapping between all-atom and reduced representation, using the reconstruction loss to facilitate the learning of coarse-grained variables. In addition, a force-matching method is applied to variationally determine the coarse-grained potential energy function. This procedure is tested on a number of model systems including single-molecule and bulk-phase periodic simulations.