First-principles calculations of the dynamical and thermodynamic properties of lead chalcogenides PbX (X = S, Se, Te)

Abstract

We perform first-principles calculations of the dynamical and thermodynamic properties of lead chalcogenides PbX (X = S, Se, Te ). Using density functional perturbation theory, we obtain the phonon frequencies and the phonon dispersion curves, as well as corresponding density of states. The calculated phonon frequencies at the Γ, X, and L points of the Brillouin zone show good agreement with the experimental values for most vibration modes. The thermodynamics properties including the phonon contribution to the Helmholtz free energy ΔF, the phonon contribution to the internal energy ΔE, the entropy S, and the constant-volume specific heat Cv are determined within the harmonic approximation based on the calculated phonon dispersion relations. The difference values of H-H298 have been also calculated and compared with the available experimental data.