  We propose an ansatz without adjustable parameters for the calculation of
dynamical structure factor. The ansatz combines quasi-particle Green's
function, especially the contribution from the renormalization factor, and the
exchange-correlation kernel from time-dependent density functional theory
together, verified for typical metals and semiconductors from plasmon
excitation regime to Compton scattering regime. It has the capability to
reconcile both small-angle and large-angle x-ray scattering (IXS) signals with
much improved accuracy, which can be used, as the theoretical base model, in
inversely inferring electronic structures of condensed matter from IXS
experimental signals directly. It may also used to diagnose thermal parameters,
such as temperature and density, of dense plasmas in x-ray Thomson scattering
experiments.
