Phase diagram of a two-dimensional system with anomalous liquid properties

TL;DR

This study uses Monte Carlo simulations to map the phase diagram of a 2D square shoulder-square well potential, revealing liquid anomalies, multiple phases, and inverse melting phenomena.

Contribution

It provides the first detailed phase diagram for this potential, highlighting the presence of liquid anomalies and inverse melting in two dimensions.

Findings

All melting lines are first order.

One melting line shows a temperature maximum.

Inverse melting occurs over a small pressure range.

Abstract

Using Monte Carlo simulation techniques, we calculate the phase diagram for a square shoulder-square well potential in two dimensions that has been previously shown to exhibit liquid anomalies consistent with a metastable liquid-liquid critical point. We consider the liquid, gas and five crystal phases, and find that all the melting lines are first order, despite a small range of metastability. One melting line exhibits a temperature maximum, as well as a pressure maximum that implies inverse melting over a small range in pressure.