Pressure dependence of the melting mechanism at the limit of overheating in Lennard-Jones crystals

TL;DR

This study investigates how pressure influences the melting process of Lennard-Jones crystals, revealing a crossover pressure where defect excitation behavior changes and the overheating temperature's relation to pressure shifts.

Contribution

It provides new insights into the pressure-dependent melting mechanism and defect dynamics at the overheating limit in Lennard-Jones crystals.

Findings

Overheating temperature increases with pressure.

A crossover pressure marks a change in defect excitation behavior.

Defect clusters dominate the melting process at high pressures.

Abstract

We study the pressure dependence of the melting mechanism of a surface free Lennard-Jones crystal by constant pressure Monte Carlo simulation. The difference between the overheating temperature($T_{OH}$) and the thermodynamical melting point($T_M$) increase for increasing pressure. When particles move into the repulsive part of the potential the properties at $T_{OH}$ change. There is a crossover pressure where the volume jump becomes pressure-independent. The overheating limit is pre-announced by thermal excitation of big clusters of defects. The temperature zone where the system is dominated by these big clusters of defects increases with increasing pressure. Beyond the crossover pressure we find that excitation of defects and clusters of them start at the same temperature scale related with $T_{OH}$.