Two-dimensional lattice-fluid model with water-like anomalies

TL;DR

This study models water-like anomalies on a two-dimensional lattice using a Mercedes Benz molecule framework, revealing phase behaviors and response functions similar to real water, including anomalies and reentrant spinodal phenomena.

Contribution

It introduces a lattice-fluid model with water-like anomalies using a generalized approximation and Monte Carlo validation, advancing understanding of water's anomalous properties.

Findings

Phase diagram with a less dense solid phase

Liquid response functions show water-like anomalies

Reentrant spinodal observed in supercooled region

Abstract

We investigate a lattice-fluid model defined on a two-dimensional triangular lattice, with the aim of reproducing qualitatively some anomalous properties of water. Model molecules are of the "Mercedes Benz" type, i.e., they possess a D3 (equilateral triangle) symmetry, with three bonding arms. Bond formation depends both on orientation and local density. We work out phase diagrams, response functions, and stability limits for the liquid phase, making use of a generalized first order approximation on a triangle cluster, whose accuracy is verified, in some cases, by Monte Carlo simulations. The phase diagram displays one ordered (solid) phase which is less dense than the liquid one. At fixed pressure the liquid phase response functions show the typical anomalous behavior observed in liquid water, while, in the supercooled region, a reentrant spinodal is observed.