Adaptive Resolution Molecular Dynamics Technique: Down to the Essential

TL;DR

This paper demonstrates that incorporating a thermodynamic force in adaptive resolution molecular dynamics simulations ensures equilibrium and improves efficiency and accuracy, enabling better simulation of complex liquids like water and ionic liquids.

Contribution

It introduces the thermodynamic force as a key ingredient for adaptive resolution MD, improving upon existing methods that rely solely on switching functions.

Findings

Thermodynamic force guarantees equilibrium between different resolution regions.

Combining thermodynamic force with thermostat enhances simulation accuracy.

Method effectively simulates complex liquids like water and ionic liquids.

Abstract

We investigate the role of the thermodynamic (TD) force, as an essential and sufficient technical ingredient for an efficient and accurate adaptive resolution algorithm. Such a force applied in the coupling region of an adaptive resolution Molecular Dynamics (MD) set-up, assures thermodynamic equilibrium between atomistically resolved and coarse-grained regions, allowing the proper exchange of molecules. We numerically prove that indeed for systems as relevant as liquid water and 1,3-dimethylimidazolium chloride ionic liquid, the combined action of the TD force and thermostat allows for computationally efficient and numerically accurate simulations, beyond the current capabilities of adaptive resolution set-ups, which employ switching functions in the coupling region.