Rare-gas solids under pressure: A path-integral Monte Carlo simulation

TL;DR

This study uses path-integral Monte Carlo simulations to analyze the effects of pressure on rare-gas solids, comparing results with experimental data and quasiharmonic approximation to understand anharmonicity and thermodynamic properties.

Contribution

It provides a detailed comparison of PIMC simulations with experimental data and QHA, highlighting anharmonic effects in rare-gas solids under pressure.

Findings

Vibrational energy increases with pressure, but more slowly than elastic energy.

Vibrational kinetic energy exceeds potential energy, with differences decreasing under pressure.

QHA accuracy improves as pressure increases.

Abstract

Rare-gas solids (Ne, Ar, Kr, and Xe) under hydrostatic pressure up to 30 kbar have been studied by path-integral Monte Carlo simulations in the isothermal-isobaric ensemble. Results of these simulations have been compared with available experimental data and with those obtained from a quasiharmonic approximation (QHA). This comparison allows us to quantify the overall anharmonicity of the lattice vibrations and its influence on several structural and thermodynamic properties of rare-gas solids. The vibrational energy increases with pressure, but this increase is slower than that of the elastic energy, which dominates at high pressures. In the PIMC simulations, the vibrational kinetic energy is found to be larger than the corresponding potential energy, and the relative difference between both energies decreases as the applied pressure is raised. The accuracy of the QHA increases for rising pressure.