Thermodynamic anomalies in a lattice model of water: Solvation properties

TL;DR

This study uses a lattice model of water to explore its thermodynamic anomalies and solvation properties, showing qualitative agreement with observed behaviors and supporting the second critical point hypothesis for supercooled water.

Contribution

It introduces a simplified lattice model that captures water's anomalous thermodynamics and solvation behavior, aligning with experimental observations and the supercooled water critical point scenario.

Findings

Model reproduces water's thermodynamic anomalies

Qualitatively matches solvation properties of hydrophobic solutes

Supports the second critical point hypothesis for supercooled water

Abstract

We investigate a lattice-fluid model of water, defined on a 3-dimensional body-centered cubic lattice. Model molecules possess a tetrahedral symmetry, with four equivalent bonding arms. The model is similar to the one proposed by Roberts and Debenedetti [J. Chem. Phys. 105, 658 (1996)], simplified by removing distinction between "donors" and "acceptors". We focus on solvation properties, mainly as far as an ideally inert (hydrophobic) solute is concerned. As in our previous analysis, devoted to neat water [J. Chem. Phys. 121, 11856 (2004)], we make use of a generalized first order approximation on a tetrahedral cluster. We show that the model exhibits quite a coherent picture of water thermodynamics, reproducing qualitatively several anomalous properties observed both in pure water and in solutions of hydrophobic solutes. As far as supercooled liquid water is concerned, the model is consistent with the second critical point scenario.