Intermolecular correlations and mean square relative displacements in C-60fullerite

We study molecular properties of the high-temperature modification of fulle rites. In the present work we calculate the intermolecular correlations and the mean square relative displacements in C-60. The Girifalco intermolecul ar potential is utilized. The calculations have been made in the whole inte rval from the equilibrium point with orientationally ordered phase up to th e spinodal temperature. To take into account the lattice anharmonicity we u se the correlative method of unsymmetrized self-consistent field. Its secon d order allows one to investigate correlations in fee latter between the ne arest. second, third and fourth neighbors. The anharmonicity has strong eff ect on the intermolecular correlations at T > 700 K, causing their drastic rise near the spinodal point. The dependence of the correlation moments on the distance between molecules and on the crystallographic direction is con sidered. We compare our results with those for solid Ar and discuss the inf luence of a special feature of the interaction potentials on the intermolec ular correlations and the mean square molecular displacements.