Properties of electron self-energies and their role in electron spectroscopies
The GW approximation for the self-energy connected with the one-electron Green's function has been very successful in predicting band structures for a large class of semiconductors and insulators. The physical basis for this approximation and general features of its nonlocality are discussed, as well as possible improvements. Besides quasiparticle energies the self-energy also gives the intrinsic
