Convergence Study of A Self-Consistent Orthogonalized-Plane-Wave Band Calculation for Hexagonal Cds

The electronic band structure of hexagonal CdS is calculated by means of a self-consistent orthogonalized-plane-wave model, using Slater's approximation for the exchange term. In order to determine the number of plane waves to be used in the Fourier expansion of the valence states, a convergence study is discussed for the starting model and for the final self-consistent model. It is concluded that the starting model is unsatisfactory from a convergence standpoint, while the self-consistent model has sufficiently well converged for 245 plane waves. The resulting band structure is presented for the high-symmetry points of the Brillouin zone. The spin-orbit splitting of the top valence band and the effective mass along the $c$ axis of the zone are calculated from this band structure. The results are then compared with experiment.