Abstract
Within many-body perturbation theory, we apply vertex corrections to various closed-shell atoms and to jellium, using a local approximation for the vertex consistent with starting the many-body perturbation theory from a Kohn-Sham Green's function constructed from density-functional theory in the local-density approximation. The vertex appears in two places—in the screened Coulomb interaction and in the self-energy —and we obtain a systematic discrimination of these two effects by turning the vertex in on and off. We also make comparisons to standard results within the usual random-phase approximation, which omits the vertex from both. When a vertex is included for closed-shell atoms, both ground-state and excited-state properties demonstrate little improvement over standard . For jellium, we observe marked improvement in the quasiparticle bandwidth when the vertex is included only in , whereas turning on the vertex in leads to an unphysical quasiparticle dispersion and work function. A simple analysis suggests why implementation of the vertex only in is a valid way to improve quasiparticle energy calculations, while the vertex in is unphysical, and points the way to the development of improved vertices for ab initio electronic structure calculations.
- Received 25 January 2007
DOI:https://doi.org/10.1103/PhysRevB.76.155106
©2007 American Physical Society