The role of d-states in semiconductors

The shift in the valence-band maxima due to pd-coupling is calculated in tight-binding theory using universal coupling matrix elements and Hartree-Fock term values. The resulting shifts are smaller than those predicted by Wei and Zunger in the Local Density Approximation, largely because d-states lie much lower, relative to the valence-band maximum, from hartree-Fock theory. Comparison with experimental energy differences indicates Hartree-Fock is more appropriate. This suggests that the much simpler theory may be preferable for estimating the valence-band shift and the many other related properties affected by d-states