Aspects on diagrammatic expansion for models related to a homogeneous electron gas
n a previous paper (see abstr. A76748 of 1974) the expansion of the irreducible self-energy of an electron gas was studied and found to give unreliable results for the satellites of the one-electron spectra function. This was due to the incorrect analytic properties of the corresponding green function. These results are confirmed and extended by studying a simple model (s-model) which allows the n