Bottom-up derivation of an effective thermostat for united atoms simulations of water

TL;DR

This paper derives effective pairwise interactions for a united atoms water model using a bottom-up approach, improving transport property predictions compared to standard models.

Contribution

It introduces a novel bottom-up method to determine dissipative and stochastic interactions in a united atoms water model, enhancing its accuracy.

Findings

Transport properties are significantly improved with the derived interactions.

The bottom-up approach outperforms the top-down method in accuracy.

Effective interactions better replicate detailed molecular dynamics results.

Abstract

In this article we derive the effective pairwise interactions in a Langevin type united atoms model of water. The interactions are determined from the trajectories of a detailed molecular dynamics simulation of simple point charge water. A standard method is used for estimating the conservative interaction, whereas a new "bottom-up" method is used to determine the effective dissipative and stochastic interactions. We demonstrate that, when compared to the standard united atoms model, the transport properties of the coarse-grained model is significantly improved by the introduction of the derived dissipative and stochastic interactions. The results are compared to a previous study, where a "top-down" approach was used to obtain transport properties consistent with those of the simple point charge water model.