Many-electron effects on transport processes in dense helium

Many-electron effects on dynamical correlations in dense helium are studied by means of self-consistent-field molecular dynamics, a computational method that combines a Hartree-Fock solution of the electronic structure of an arbitrary collection of atoms with molecular dynamics. Pair correlation functions, velocity autocorrelation functions, and coefficients of self-diffusion are calculated for helium at densities between 0.1 and 1.5 g/${\mathrm{cm}}^3$ and at temperatures of 1 and 5 eV. Comparisons are made to results computed with semiempirical pair potentials derived from low- and high-density experimental data. With increasing density, the self-consistent-field molecular-dynamics results progressively diverge from the results of molecular-dynamics simulations using Hartree-Fock pair potentials, reflecting the onset of many-atom screening effects within local clusters of atoms. This dynamic screening results in a 30% increase in the diffusion coefficient over that obtained in a molecular-dynamics simulation employing pair interaction potentials.