Deconstructing classical water models at interfaces and in bulk

TL;DR

This paper deconstructs classical water models into short and long-range components, revealing how different interactions influence water's properties and interfaces, and providing insights for improving these models.

Contribution

It introduces a method to separate and analyze the roles of local hydrogen bonds and long-range interactions in classical water models using perturbation and local molecular field theories.

Findings

Short-range models accurately reproduce local hydrogen bond structures.

Long-range interactions significantly affect water's anomalous properties.

Insights into hydrophobic interface behavior and model refinement are provided.

Abstract

Using concepts from perturbation and local molecular field theories of liquids we divide the potential of the SPC/E water model into short and long ranged parts. The short ranged parts define a minimal reference network model that captures very well the structure of the local hydrogen bond network in bulk water while ignoring effects of the remaining long ranged interactions. This deconstruction can provide insight into the different roles that the local hydrogen bond network, dispersion forces, and long ranged dipolar interactions play in determining a variety of properties of SPC/E and related classical models of water. Here we focus on the anomalous behavior of the internal pressure and the temperature dependence of the density of bulk water. We further utilize these short ranged models along with local molecular field theory to quantify the influence of these interactions on the structure of hydrophobic interfaces and the crossover from small to large scale hydration behavior. The implications of our findings for theories of hydrophobicity and possible refinements of classical water models are also discussed.