Eur. Phys. J. B (2016) 89: 238
https://doi.org/10.1140/epjb/e2016-70028-4

Colloquium

The GW plus cumulant method and plasmonic polarons: application to the homogeneous electron gas^*

Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK

^a e-mail: fabio.caruso@materials.ox.ac.uk

Received: 15 January 2016
Published online: 2 November 2016

Abstract

We study the spectral function of the homogeneous electron gas using many-body perturbation theory and the cumulant expansion. We compute the angle-resolved spectral function based on the GW approximation and the “GW plus cumulant” approach. In agreement with previous studies, the GW spectral function exhibits a spurious plasmaron peak at energies 1.5ω_pl below the quasiparticle peak, ω_pl being the plasma energy. The GW plus cumulant approach, on the other hand, reduces significantly the intensity of the plasmon-induced spectral features and renormalizes their energy relative to the quasiparticle energy to ω_pl. Consistently with previous work on semiconductors, our results show that the HEG is characterized by the emergence of plasmonic polaron bands, that is, broadened replica of the quasiparticle bands, red-shifted by the plasmon energy.