Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential

TL;DR

This paper investigates liquid anomalies in the Stell-Hemmer potential through analytical and numerical methods, revealing structural and thermodynamic peculiarities that suggest a possible liquid-liquid phase transition.

Contribution

It provides the first combined analytical and numerical analysis of liquid anomalies in the Stell-Hemmer potential, linking structural features to thermodynamic behavior.

Findings

Anomalous decrease in volume and compressibility with heating.

Increase in diffusion coefficient with pressure.

Evidence supporting a potential liquid-liquid phase transition.

Abstract

We study the Stell-Hemmer potential using both analytic (exact $1d$ and approximate $2d$) solutions and numerical $2d$ simulations. We observe in the liquid phase an anomalous decrease in specific volume and isothermal compressibility upon heating, and an anomalous increase in the diffusion coefficient with pressure. We relate the anomalies to the existence of two different local structures in the liquid phase. Our results are consistent with the possibility of a low temperature/high pressure liquid-liquid phase transition.