Cell-cluster expansion for an anharmoníc solid

The cell-cluster method is applied to the calculation of the thermodynamic properties of an anharmonic crystal, in the classical limit. The partition function is expressed as a series of multidimensional integrals in real space, the first two of which are evaluated numerically to high accuracy. The method is applied to a model of xenon including Mie-Lennard-Jones interactions between nearest-neighbor atoms, giving results in good agreement with experiment. The application of the method to a harmonic crystal, and the relationship with anharmonic perturbation theory, are also discussed.