Many-atom screening effects on diffusion in dense helium

The structure and dynamics of helium at 5 eV over the density range 1.5≤ρ≤8 g/${\mathrm{cm}}^3$ were studied using self-consistent-field molecular dynamics. Representative results for the pair-correlation function, velocity autocorrelation function, and the average charge density surrounding an atom are presented. Many-atom screening is found to have an important effect on all of these quantities above 0.3 g/${\mathrm{cm}}^3$. Above 2 g/${\mathrm{cm}}^3$, screening effects appear to saturate, and the coefficient of diffusion tends to the limit of a one-component plasma.