The influence of boundaries on high pressure melting experiments

TL;DR

This study uses Monte Carlo simulations to investigate how different boundary conditions affect high-pressure melting behavior of argon slabs, revealing that boundary rigidity influences whether melting initiates at the surface or via lattice instability.

Contribution

It introduces a simulation approach to analyze boundary effects on melting under pressure, highlighting the impact of boundary medium rigidity on melting mechanisms.

Findings

Rigid boundary leads to lattice instability-driven melting.

Soft boundary causes surface-initiated melting at lower temperatures.

Boundary conditions significantly influence melting behavior.

Abstract

At low pressure, free surfaces play a crucial role in the melting transition. Under pressure, the surface of the sample is acted upon by some pressure transmitting medium. To examine the effect of this medium on melting, we performed Monte Carlo simulations of a system of argon atoms in the form of a slab with two boundaries. We examined two cases, one with a soft and the other with a rigid medium at the boundaries. We found that in the presence of a rigid medium, melting resembles the mechanical lattice instability found in a surface-free solid. With a soft medium at the boundary, melting begins at the surface and at a lower temperature. The relevance of these results to experiment is discussed.