title: Band-gap problem in semiconductors revisited: effects of core states and many-body self-consistency.
abstract: A novel picture of the quasiparticle (QP) gap in prototype semiconductors Si and Ge emerges from an analysis based on all-electron, self-consistent, GW calculations. The deep-core electrons are shown to play a key role via the exchange diagram-if this effect is neglected, Si becomes a semimetal. Contrary to current lore, the Ge 3d semicore states (e.g., their polarization) have no impact on the GW gap. Self-consistency improves the calculated gaps-a first clear-cut success story for the Baym-Kadanoff method in the study of real-materials spectroscopy; it also has a significant impact on the QP lifetimes. Our results embody a new paradigm for ab initio QP theory.
authors.affiliation: Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Ku
authors.forename: Adolfo G
authors.initials: AG
authors.lastname: Eguiluz