Thermodynamic, Dynamic and Structural Anomalies for Shoulder-like potentials

TL;DR

This study uses molecular dynamics to explore how different core-softened potentials influence the presence of thermodynamic, dynamic, and structural anomalies, revealing that the potential shape determines whether these anomalies occur.

Contribution

It demonstrates how the shape of core-softened potentials predicts the existence of anomalies, linking potential features to phase diagram behavior.

Findings

Anomalies occur when the shoulder is repulsive or has a small well.

Deep attractive wells at the closest scale suppress anomalies.

Potential shape predicts the presence or absence of anomalies.

Abstract

Using molecular dynamic simulations we study a family of continuous core-softened potentials consisting of a hard core, a shoulder at closest distances and an attractive well at further distance. The repulsive shoulder and the well distances represent two length scales. We show that if the first scale, the shoulder, is repulsive or has a small well, the potential has a region in the pressure-temperature phase diagram with density, diffusion and structural anomalies. However, if the closest scale becomes a deep attractive well the regions in the pressure-temperature phase diagram where the three anomalies are present shrink and disappear. This result enables us to predict by the shape of the core-softened potential if anomalies would or would not be present.