Density Distribution in a Hard-Sphere Crystal

We performed extensive Monte Carlo simulations of a hard-sphere f.c.c. crystal near the melting transition in order to examine the validity of the widely used Gaussian ansatz for the density distribution in solids. Anisotropic deviations in the shape of the density distribution from the Gaussian form are found to be of the order of 10%. Popular liquid-based density functional approximations are shown to fail in predicting the magnitude and the qualitative features of the anisotropy in the crystalline density distributions.