Ab initioand classical molecular dynamics of neon melting at high pressure

Abstract

First-principles and classical molecular dynamics calculations have been performed to study the high-pressure melting curve of Ne. In the low temperature region, simulations with solid and liquid in coexistence (two-phase) with a Lennard-Jones interatomic potential well reproduce experimental findings. As anticipated, there is a melting temperature overestimation when heating a crystal (one-phase) compared to the two-phase results. Furthermore, there is a significant discrepancy comparing the one-phase ab initio curve to previously reported classical predictions: at $150\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, the calculations in this work show a melting temperature approximately $1000\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ above the estimate based on an exponential-6 potential. However, there is a close match between the one-phase ab initio curve and the classical one-phase results in this work. This could also imply an agreement between a two-phase ab initio and classical two-phase melting curve. Therefore, considering the documented accuracy of the coexistence method, the classical two-phase melting in this work could well indicate the most probable melting behavior. In conjunction with recent theoretical results for Xe, no significant melting slope decrease was observed for Ne in this study.