Lattice dynamics, thermodynamic and elastic properties of CdGeAs2

Abstract

An extended Keating’s model with two-bond-stretching and one-angle-bending force constants within the rigid-ion approximation is applied to the investigation of the lattice dynamics of CdGeAs2. Five model parameters of the theory are determined by a least-square fitting to the infrared reflectivity measurements. The phonon spectrum along two high-symmetry directions and the one-phonon density of states are calculated. The theoretical values of the elastic constants, the constant-volume specific heat and the Debye temperature show a reasonable agreement with the experimental data reported by other authors.