Atomic kinetic energy, momentum distribution and structure of solid neon at zero-temperature

TL;DR

This paper uses diffusion Monte Carlo to accurately calculate the atomic kinetic energy, momentum distribution, and structural properties of solid neon at zero temperature, showing excellent agreement with experimental data and previous simulations.

Contribution

It presents a detailed quantum Monte Carlo study of solid neon's ground-state properties, including kinetic energy and structural features, with comparisons to experimental and theoretical results.

Findings

Atomic kinetic energy at equilibrium density is 41.51(6) K.

One-body density function fits a Gaussian curve.

Solid Ne exhibits notable anharmonic effects compared to harmonic models.

Abstract

We report on the calculation of the ground-state atomic kinetic energy, $E_{k}$, and momentum distribution of solid Ne by means of the diffusion Monte Carlo method and Aziz HFD-B pair potential. This approach is shown to perform notably for this crystal since we obtain very good agreement with respect to experimental thermodynamic data. Additionally, we study the structural properties of solid Ne at densities near the equilibrium by estimating the radial pair-distribution function, Lindemann's ratio and atomic density profile around the positions of the perfect crystalline lattice. Our value for $E_{k}$ at the equilibrium density is $41.51(6)$ K, which agrees perfectly with the recent prediction made by Timms {\it et al.}, $41(2)$ K, based on their deep-inelastic neutron scattering experiments carried out over the temperature range $4 - 20$ K, and also with previous path integral Monte Carlo results obtained with the Lennard-Jones and Aziz HFD-C2 atomic pairwise interactions. The one-body density function of solid Ne is calculated accurately and found to fit perfectly, within statistical uncertainty, to a Gaussian curve. Furthermore, we analyze the degree of anharmonicity of solid Ne by calculating some of its microscopic ground-state properties within traditional harmonic approaches. We provide insightful comparison to solid $^4$He in terms of the Debye model, in order to size the relevance of anharmonic effects in Ne.