Potential Energy Landscape of TIP4P/2005 water

TL;DR

This study thoroughly analyzes the potential energy landscape of the TIP4P/2005 water model, demonstrating a Gaussian landscape description's effectiveness and predicting a liquid-liquid critical point through an equation of state.

Contribution

It provides the first comprehensive numerical characterization of the energy landscape for TIP4P/2005 water, linking landscape properties to phase diagram features.

Findings

Gaussian landscape description fits model properties

Landscape properties align with density maxima in phase diagram

Equation of state predicts a liquid-liquid critical point

Abstract

We report an exhaustive numerical study of the statistical properties of the potential energy landscape of TIP4P/2005, one of the most accurate rigid water models. We show that, in the region where equilibrated configurations can be generated, a Gaussian landscape description is able to properly describe the model properties. We also find that the volume dependence of the landscape properties is consistent with the existence of a locus of density maxima in the phase diagram. The landscape-based equation of state accurately reproduces the TIP4P/2005 pressure-vs-volume curves, providing a sound extrapolation of the free-energy at low T. A positive-pressure liquid-liquid critical point is predicted by the resulting free-energy.