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Correlation energy for the homogeneous electron gas: Exact Bethe-Salpeter solution and an approximate evaluation

Autor(en)
Emanuele Maggio, Georg Kresse
Abstrakt

The correlation energy of the homogeneous electron gas is evaluated by solving the Bethe-Salpeter equation (BSE) beyond the Tamm-Dancoff approximation for the electronic polarization propagator. The BSE is expected to improve on the random-phase approximation, owing to the inclusion of exchange diagrams. For instance, since the BSE reduces in second order to Møller-Plesset perturbation theory, it is self-interaction free in second order. Results for the correlation energy are compared with quantum Monte Carlo benchmarks and excellent agreement is observed. For low densities, however, we find imaginary eigenmodes in the polarization propagator. To avoid the occurrence of imaginary eigenmodes, an approximation to the BSE kernel is proposed that allows us to completely remove this issue in the low-electron-density region. We refer to this approximation as the random-phase approximation with screened exchange (RPAsX). We show that this approximation even slightly improves upon the standard BSE kernel.

Organisation(en)
Computergestützte Materialphysik
Journal
Physical Review B
Band
93
Anzahl der Seiten
12
ISSN
1098-0121
DOI
https://doi.org/10.1103/PhysRevB.93.235113
Publikationsdatum
06-2016
Peer-reviewed
Ja
ÖFOS 2012
103025 Quantenmechanik, 103036 Theoretische Physik, 103015 Kondensierte Materie, 103009 Festkörperphysik
Schlagwörter
ASJC Scopus Sachgebiete
Electronic, Optical and Magnetic Materials, Condensed Matter Physics
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/584dace5-067d-4f52-acdf-1262bb45cc51