Structure of Dense Krypton Gas: Percus-Yevick and Monte Carlo Results

Abstract

Monte Carlo calculations of the pair correlation function g(r) and numerical solutions of the Percus-Yevick equation are reported for a Lennard-Jones potential, the krypton potential of Barker et al. and a long range three-body (triple dipole and dipole-dipole-quadrupole) potential at 297 K and densities between 2 and 14 × 10²⁷ atoms/m³. We compare in real and Fourier space, and also calculate the pressure and compressibility. The latter two quantities are compared to experimental data on the 297 K isotherm, and while the PY results are in agreement the Barker et al. potential results are significantly different for ρ > 3 × 10²⁷ atoms/m³.

It is found that if the point where u(r) = 0 is chosen appropriately either Lennard-Jones or Barker et al. potential would yield a reasonable fit to the structure factor, S(q), for q > 2 Å⁻¹. The shape of the attractive part of the potential influences S(q) mainly for q < 1 Å⁻¹. Except at values of q < 2 Å⁻¹ the effect of three-body forces on the structure factor is negligible at the state (ρ = 14 × 10²⁷) studied here.