Electronic band structures for zinc-blende and wurtzite CdS

The electronic band structures for zinc-blende and wurtzite CdS are calculated within the local-density approximation with the use of first-principles pseudopotentials. Incorporating the $d$ state into the valence band improves substantially the main-valence-band width, and yields valence-band features in good agreement with experiment. The maximum effect of the $d$ band occurs at ${\Gamma }_{15}$ for zinc-blende CdS and at ${\Gamma }_1$,${\Gamma }_6$ for wurtzite CdS. We find that the local-density approximation does not predict accurately the position of localized Cd $4d$ state.