Ice polyamorphism in the minimal Mercedes-Benz model of water

TL;DR

This study explores the phase behavior of a minimal 2D water model, revealing a first-order transition between crystalline and amorphous phases and a reversible, continuous transformation between two amorphous structures, highlighting key aspects of water polyamorphism.

Contribution

It demonstrates the existence of both first-order and continuous amorphous-amorphous transitions in a minimal water model, providing insights into the fundamental mechanisms of polyamorphism.

Findings

First-order transition between crystalline and high-density amorphous phases.

Reversible, continuous transformation between high- and low-density amorphous phases.

Low-density amorphous phase lacks structural stability.

Abstract

We investigate ice polyamorphism in the context of the two-dimensional Mercedes-Benz model of water. We find a first-order phase transition between a crystalline phase and a high-density amorphous phase. Furthermore we find a reversible transformation between two amorphous structures of high and low density; however we find this to be a continuous and not an abrupt transition, as the low-density amorphous phase does not show structural stability. We discuss the origin of this behavior and its implications with regard to the minimal generic modeling of polyamorphism.