Valence-band structure of cubic CdS as determined by angle-resolved photoemission

The valence-band structure of cubic CdS along the {Γ}-{Σ}-X direction and at all high-symmetry points has been experimentally determined using angle-resolved photoemission and compared to two local density approximation (LDA) calculations as well as to a recent quasiparticle calculation. The Cd 4d level was found to be semibandlike with an energy dispersion of up to 1 eV. The energy difference between the experimental and our calculated linear-muffin-tin orbital (LMTO) LDA energies falls, as expected, along a line of positive gradient. The quasiparticle calculation by Pollmann and co-workers fits the experimental values somewhat better than the LMTO calculation, although a difference of {~}1.0 eV was still found to occur for the Cd 4d band. The self-interaction and relaxation-corrected pseudopotential LDA results by the same group give the best fit to within {~}±{}0.5 eV for nearly all critical energies measured. Comparison with previously reported photoemission results on the wurtzite structure shows that energies at equivalent symmetry points agree within experimental error.