Quasi Harmonic Lattice Dynamics and Molecular Dynamics calculations for the Lennard-Jones solids

TL;DR

This paper combines Molecular Dynamics, Quasi Harmonic Lattice Dynamics, and Energy Minimization to accurately model the pressure and temperature dependence of noble gas solids, introducing new Lennard-Jones parameters.

Contribution

It introduces a combined approach using QHLD and MD to match experimental densities across a range of conditions and proposes new LJ parameters for Ne, Kr, and Xe.

Findings

Accurate density predictions from 0 K to melting.

New Lennard-Jones parameters for Ne, Kr, and Xe.

Insight into melting related to solid instability.

Abstract

We present Molecular Dynamics (MD), Quasi Harmonic Lattice Dynamics (QHLD) and Energy Minimization (EM) calculations for the crystal structure of Ne, Ar, Kr and Xe as a function of pressure and temperature. New Lennard-Jones (LJ) parameters are obtained for Ne, Kr and Xe to reproduce the experimental pressure dependence of the density. We employ a simple method which combines results of QHLD and MD calculations to achieve densities in good agreement with experiment from 0 K to melting. Melting is discussed in connection with intrinsic instability of the solid as given by the QHLD approximation. (See http://www.fci.unibo.it/~valle for related papers)