A1 Journal article (refereed)
Dynamically screened vertex correction to GW (2020)

Pavlyukh, Y., Stefanucci, G., & van Leeuwen, R. (2020). Dynamically screened vertex correction to GW. Physical Review B, 102(4), Article 045121. https://doi.org/10.1103/PhysRevB.102.045121

JYU authors or editors

Van Leeuwen, Robertus

Publication details

All authors or editors: Pavlyukh, Yaroslav; Stefanucci, Gianluca; van Leeuwen, Robert

Journal or series: Physical Review B

ISSN: 2469-9950

eISSN: 2469-9969

Publication year: 2020

Volume: 102

Issue number: 4

Article number: 045121

Publisher: American Physical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/PhysRevB.102.045121

Publication open access: Not open

Publication channel open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/71363

Web address of parallel published publication (pre-print): https://arxiv.org/abs/2004.05344

Abstract

Diagrammatic perturbation theory is a powerful tool for the investigation of interacting many-body systems, the self-energy operator Sigma encoding all the variety of scattering processes. In the simplest scenario of correlated electrons described by the GW approximation for the electron self-energy, a particle transfers a part of its energy to neutral excitations. Higher-order (in screened Coulomb interaction W) self-energy diagrams lead to improved electron spectral functions (SFs) by taking more complicated scattering channels into account and by adding corrections to lower order self-energy terms. However, they also may lead to unphysical negative spectral functions. The resolution of this difficulty has been demonstrated in our previous works. The main idea is to represent the self-energy operator in a Fermi golden rule form which leads to a manifestly positive definite SF and allows for a very efficient numerical algorithm. So far, the method has only been applied to the three-dimensional electron gas, which is a paradigmatic system, but a rather simple one. Here we systematically extend the method to two dimensions including realistic systems such as monolayer and bilayer graphene. We focus on one of the most important vertex function effects involving the exchange of two particles in the final state. We demonstrate that it should be evaluated with the proper screening and discuss its influence on the quasiparticle properties.

Keywords: condensed matter physics; quantum physics; approximation

Fields of science: