Lattice dynamics study of lead chalcogenides

First principal calculations have been performed to study the structural and lattice-dynamical properties for lead chalcogenides compounds: PbS, PbSe and PbTe. The ground-states quantities such as the lattice parameter and bulk modulus were evaluated using the plane wave pseudo-potential method within the density-functional theory. Phonon dispersion spectra were derived from linear-response to density-functional theory. We have examined particularly the effect of pressure on the dynamical charges, longitudinal optical (LO), transverse optical (TO), and the splitting of LO–TO branches. The obtained results regarding dynamical properties under pressure have been confronted to the common III–V semiconductors. Finally thermodynamics quantities were reported by means of the quasiharmonic approximation.