The influence of anharmonicities to the lattice structure of rare gas crystals

The zero-point energy and the leading anharmonic terms of the free energy retained in second-order perturbation theory are calculated numerically at temperature zero for the two closest-packed structures, the face-centered cubic (fcc) and the hexagonal closest-packed (hcp). In agreement with experiment we get the fcc lattices energetically favoured relative to the hep lattices.