Complex phase diagram from simple interactions in a one-component system

TL;DR

This study demonstrates that simple, spherically symmetric interactions can produce complex, water-like phase diagrams with multiple crystalline structures and anomalous behaviors, challenging the notion that complexity requires intricate interactions.

Contribution

It shows that simple pair potentials with volume discontinuities can generate complex phase diagrams similar to water, highlighting that complexity can arise from simple interactions.

Findings

Water-like anomalies observed in simulations

Multiple crystalline structures identified

Complex phase behavior from simple potentials

Abstract

The pressure-temperature phase diagram of a one-component system, with particles interacting through a spherically symmetric pair potential is studied. It is shown that if the pair potential allows for a discontinuous reduction of the volume of the system when pressure is increased (at zero temperature), then the phase diagram obtained has many ``water like'' characteristics. Among these characteristics the negative thermal expansion and expansion upon freezing in some range of pressure, and the existence of many different crystaline structures are clearly observable in numerical simulations. This implies that complex phase diagrams are not necessarily originated in complex microscopic interactions.