Modeling Diffusive Dynamics in Adaptive Resolution Simulation of Liquid Water

TL;DR

This paper develops a dual-resolution molecular dynamics simulation of liquid water using an adaptive scheme, enabling on-the-fly resolution changes and matching diffusional dynamics across models to accurately reproduce water's properties.

Contribution

It introduces a methodology to align diffusional dynamics between coarse-grained and all-atom water models within an adaptive simulation framework.

Findings

The adaptive scheme accurately reproduces structural properties of water.

The methodology ensures consistent diffusional behavior across resolutions.

The approach captures thermodynamic and dynamical properties of water at ambient conditions.

Abstract

We present a dual-resolution molecular dynamics (MD) simulation of liquid water employing a recently introduced Adaptive Resolution Scheme (AdResS). The spatially adaptive molecular resolution procedure allows for changing from a coarse-grained to an all-atom representation and vice-versa on-the-fly. In order to find the most appropriate coarse-grained water model to be employed with AdResS we first study the accuracy of different coarse-grained water models in reproducing the structural properties of the all-atom system. Typically, coarse-grained molecular models have a higher diffusion constant than the corresponding all-atom models due to the reduction in degrees of freedom (DOFs) upon coarse-graining that eliminates the fluctuating forces associated with those integrated-out molecular DOFs. Here, we introduce the methodology to obtain the same diffusional dynamics across different resolutions. We show that this approach leads to the correct description of essential thermodynamic, structural and dynamical properties of liquid water at ambient conditions.