Dynamical density response of II-VI semiconductors

We report results of ab initio calculations of the dynamical density response in CdTe, CdS, and CdSe. The calculated loss functions in all these semiconductors are rich in fine structures and show a rather unusual, negative dispersion of the loss peak due to the interaction of interband transitions with the plasmon. The detailed shape of the loss function in these compounds is strongly affected by various factors, such as the presence of occupied semicore Cd-$4d$ states, the self-energy effects which shift down these states to the experimentally observed position, and electron-hole vertex corrections in screening.