Minimal microscopic model for liquid polyamorphism and water-like anomalies

TL;DR

This paper introduces a minimal theoretical model that captures liquid polyamorphism and water-like anomalies by transforming a binary lattice system into a single-component fluid with two states, explaining diverse phase behaviors.

Contribution

It presents a novel minimal model that unifies the understanding of liquid polyamorphism and anomalies in water-like liquids through a simple interconversion mechanism.

Findings

Phase diagram reveals liquid-liquid transition with a critical point.

The model explains thermodynamic anomalies without polyamorphism.

Unifies supercooled water behavior with other polyamorphic liquids.

Abstract

Liquid polyamorphism is the intriguing possibility for a single component substance to exist in multiple liquid phases. We propose a minimal model for this phenomenon. Starting with a binary lattice model with critical azeotropy and liquid-liquid demixing, we allow interconversion of the two species, turning the system into a single-component fluid with two states differing in energy and entropy. Unveiling the phase diagram of the non-interconverting binary mixture gives unprecedented insight on the phase behaviors accessible to the interconverting fluid, such as a liquid-liquid transition with a critical point, or a singularity-free scenario, exhibiting thermodynamic anomalies without polyamorphism. The model provides a unified theoretical framework to describe supercooled water and a variety of polyamorphic liquids with water-like anomalies.