Abstract
A tensor force model, including up to four nearest-neighbor interactions, which is in satisfactory agreement with inelastic-neutron-diffraction data and with elastic constants, has been obtained. The results of calculations based on this model, of the frequency spectrum and its moments, the specific heat, and the Debye-Waller factor are presented. The concept of equivalent Debye temperatures is used extensively. Results for the thermal properties are believed to be reliable, and are compared with x-ray intensity measurements and with Cp and related thermodynamic measurements. An estimate of the electronic specific heat proposed by Heiniger is employed. Reasonable agreement between theory and experiment is obtained.