Spectral properties of quasiparticles in a semiconductor

The one-electron excitation spectrum of the prototype semiconductor Si has been obtained from a first principles calculation of the spectral-weight function A((q) over right arrow, omega) of the interacting one-electron Green's function. The Dyson equation has been solved with the self-energy operator obtained in the GW approximation, where the bare propagator G and the omega-dependent screening matrix W, without (random-phase approximation) and with (time-dependent local density approximation) vertex corrections, have been computed within Kohn-Sham-local-density-approximation theory. Positions of quasiparticle peaks (i.e., the ''band structure''), their lifetimes, and satellite (plasmaron) spectral structures are extracted in a broad energy range. [S0163-1829(97)08140-X].