Abstract
The recent discovery of novel lead chalcogenide-based thermoelectric materials has attracted great
interest. These materials exhibit low thermal conductivity which is closely related to their lattice
dynamics and thermodynamic properties. In this paper, we report a systematic study of electronic
structures and lattice dynamics of the lead chalcogenides PbX (X=Te, Se, S) using first-principles
density functional theory calculations and a direct force-constant method. We calculate the struc-
tural parameters, elastic moduli, electronic band structures, dielectric constants, and Born effective
charges. Moreover, we determine phonon dispersions, phonon density of states, and phonon softening
modes in these materials. Based on the results of these calculations, we further employ quasihar-
monic approximation to calculate the heat capacity, internal energy, and vibrational entropy. The
obtained results are in good agreement with experimental data. Lattice thermal conductivities are evaluated in terms of the Gruneisen parameters. The mode Gruneisen parameters are calculated to explain the anharmonicity in these materials. The effect of the spin-orbit interaction is found to be
negligible in determining the thermodynamic properties of PbTe, PbSe, and PbS.
