Atomic kinetic energy, momentum distribution and structure of solid neon at zero-temperature
Abstract
We report on the calculation of the ground-state atomic kinetic energy, Ek, 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 Ek at the equilibrium density is 41.51(6) K, which agrees perfectly with the recent prediction made by Timms 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 4He in terms of the Debye model, in order to size the relevance of anharmonic effects in Ne.