Simple classical calculation of thermal expansion for rare-gas solids

We report the results of a simple model calculation of the thermal expansion for rare-gas solids. Using the Lennard-Jones interatomic potential-energy function and the Debye spectrum for the vibrational frequencies, the time-averaged interatomic spacing is calculated as a function of temperature. Despite its simplicity, the model yields results that are in good to excellent agreement with the experimental data for Ne, Ar, Kr, and Xe. In most cases the results turn out to be more accurate than those obtained from the improved self-consistent phonon theory and are comparable to the self-consistent average phonon calculations.