DYNAMICAL DENSITY RESPONSE OF II-VI SEMICONDUCTORS

We report results of ab initio calculations of the dynamical density r esponse in CdTe, CdS, and CdSe. The calculated loss functions in all t hese semiconductors are rich in fine structures and show a rather unus ual, negative dispersion of the loss peak due to the interaction of in terband transitions with the plasmon. The detailed shape of the loss f unction in these compounds is strongly affected by various factors, su ch as the presence of occupied semicore Cd-4d states, the self-energy effects which shift down these states to the experimentally observed p osition, and electron-hole Vertex corrections in screening.