Local environment and distribution of near neighbors for an ion in a hot dense matter

Abstract

I report the study of spatial and angular distribution of nearest and next-nearest neighbor ions around a test ion in a hot dense matter, for ion–ion coupling parameter Γ ii ranging from Γ ii ≪ 1 to Γ ii = 20. Results from three types of simulations are presented. The first is a quantum Monte Carlo for free electrons and ions. The second is an ions-only fast molecular dynamics with screened Coulomb (Yukawa) interaction between ions. The third is a classical molecular dynamics for point-like free electrons and ions. The results of the simulations agree very well. General trends are outlined for dependence of the neighbor distributions on density ρ and temperature T. Effects of an ionization composition and screening on the near neighbor distributions (as functions of chemical element, ρ and T) give rise to interesting physics, which is discussed. Analytic expressions are presented for distributions of distances to the nearest and next-nearest neighbor ions, for 0 ≤ Γ ii ≤ 20. Distribution of angle between directions to the nearest and next-nearest neighbor ion is also investigated.