Theoretical Phonon Spectra and Heat Capacities of Solidified Argon and Krypton

The phonon spectra of solidified Argon and Krypton have been calculated on the basis of the Born‐Karman theory using the interatomic potential ϕ( r ) = ‐ Ar −6 + AB × exp (‐ r/Q ), and taking into account the zero‐point energy and interactions of the four nearest neighbours. The evaluation of the parameters A , B , and Q requires a knowledge of the vibration spectrum of the crystal which is itself a function of these constants. A method of iteration is therefore employed to evaluate the potential parameters, after estimating the frequency‐dependent terms using the Debye theory of specific heats. The static lattice energy is obtained by a method of successive approximations. The specific heats and (θ, T ) curves show a fair agreement with the experimental results.