Relativistic electronic structure of the NaCl polymorph of CdS

The energy-band structure of the high-pressure (NaCl) phase of CdS has been calculated using a fully-relativistic symmetrized augmented-plane-wave method. The results have been used to obtain density-of-state histograms over a 30-eV range. Our results indicate that CdS, in this phase, is an indirect-gap semiconductor. The calculated forbidden band gap of 1.5 eV is in good agreement with experimental data. There is, however, no experimental information on the location and nature of the gap for further comparison. The valence band has two nearly degenerate maxima at $L$ and at ($\frac{\pi }{a}$) (1,1,0) in the $\Sigma$ directions. The conduction band, similarly, has one minimum at $\Gamma$ and another set at $X$ with almost the same energy.