title: Vertex Corrections for Positive-Definite Spectral Functions of Simple Metals.
abstract: We present a systematic study of vertex corrections in a homogeneous electron gas at metallic densities. The vertex diagrams are built using a recently proposed positive-definite diagrammatic expansion for the spectral function. The vertex function not only provides corrections to the well known plasmon and particle-hole scatterings, but also gives rise to new physical processes such as the generation of two plasmon excitations or the decay of the one-particle state into a two-particle-one-hole state. By an efficient Monte Carlo momentum integration we are able to show that the additional scattering channels are responsible for a reduction of the bandwidth, the appearance of a secondary plasmon satellite below the Fermi level, and a substantial redistribution of spectral weights. The feasibility of the approach for first-principles band-structure calculations is also discussed.
authors.affiliation: Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany and Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, P.O. Box 3049, 67653 Kaiserslautern, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Pavlyukh
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: A-M
authors.initials: AM
authors.lastname: Uimonen
authors.affiliation: Dipartimento di Fisica and European Theoretical Spectroscopy Facility (ETSF), Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy and INFN, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Stefanucci
authors.affiliation: Department of Physics and European Theoretical Spectroscopy Facility (ETSF), Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland.
authors.forename: R
authors.initials: R
authors.lastname: van Leeuwen