FULLY RELATIVISTIC ELECTRONIC-STRUCTURE OF THE SEMICONDUCTORS PBTE, PBSE AND PBS

We present a fully relativistic band structure and the corresponding e lectronic density of states for the lead salts PbTe, PbSe and PbS, cal culated using the parametrized linear combination of atomic orbitals o f Slater and Koster, and the Vogl basis {sp(3)s}. We substitute for t he pure atomic orbitals, symmetrically orthogonalized orbitals, throug h the Lowdin process; we consider only nearest-neighbours, and replace the actual hamiltonian with a pseudo-hamiltonian which includes the o rthogonalization terms of the basis. The density of states was calcula ted by the tetrahedral division of the Brillouin zone and linear inter polation. Our results show that with this simple model, diagonalizing a 20 x 20 matrix with only 13 adjustable parameters, it is possible to reproduce the valence and lower conduction bands of a fully relativis tic calculation done with the local empirical pseudo potential method.