In this work two aspects of momentum-dependent electron energy loss spectrometry are studied,
both in the core-loss and in the low-loss region. In the case of core losses, we focus on the demonstration and
the interpretation of an unexpected non-Lorentzian behavior in the angular part of the double-differential
scattering cross-section. The silicon L3 edge is taken as an example. Using calculations we show that the
non-Lorentzian behavior is due to a change in the wavefunction overlap between the initial and the final
states. In the case of low losses, we first analyze the momentum-dependent loss functions of coinage metals
Cu, Ag, and Au. We then demonstrate how advanced electronic structure calculations can be used to
build simple models for the dielectric function that can then serve as a basis for the calculation of more
complicated sample geometries.