Calculation of heat capacity and mean-square deviations on phonon spectra for crystals with BCC and FCC lattices

The paper considers the dynamics of monatomic cubic crystal lattices under the influence of the interatomic forces of Van der Waals nature. Using the adiabatic approximation, the authors received and solved a system of equations describing vibrations of monatomic BCC and FCC lattices, realized the longwave principle, which allowed to express the force constants of the dynamical model in terms of elastic constants of a given substance and to calculate phonon spectra and temperature dependences of heat capacity and mean-square deviations for some crystals with BCC and FCC lattices.