AB-INITIO CALCULATIONS OF THE DYNAMIC-RESPONSE OF BERYLLIUM

We present results from ab initio calculations of the full inverse die lectric matrix of beryllium, from which we obtain the dynamic scatteri ng cross section. This is shown to be in excellent agreement with rece nt inelastic x-ray-scattering experiments, both in overall shape and i n precise details of the fine structure. As the calculations have been performed entirely within the random-phase approximation, this presen ts conclusive evidence that band-structure effects are responsible for the observed structure.