A new phonon distribution model was developed to provide a precise and reliable equation for lattice heat capacity at constant volume, e.g. for the resolution of excess thermophysical properties. Because this equation has a single characteristic temperature as a parameter determined after assignment of the other parameters available from chemical, crystallographical, and/or elastic information, it is relatively easy to fit the model to the experimental heat-capacity data. It is based on the harmonic oscillator model and, therefore, may require adjustment at high sub-ambient temperatures or super-ambient regions. Three FORTRAN IV computer programs provide convenient devices to calculate the apparent characteristic temperatures from given heat-capacity values, to calculate lattice heat-capacity values for given characteristic temperatures, and to compare the (model) predicted heat capacity with experimental heat-capacity values.