Dynamically screened vertex correction to GW
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
Published inPhysical Review B
©2020 American Physical Society
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. ...
PublisherAmerican Physical Society
Publication in research information system
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Related funder(s)Academy of Finland
Funding program(s)Academy Project, AoF
Additional information about fundingThework has been performed under the Project HPC-EUROPA3(INFRAIA-2016-1-730897), with the support of the EC Re-search Innovation Action under the H2020 Programme; inparticular, Y.P. gratefully acknowledges the computer re-sources and technical support provided the CSC-IT Centerfor Science (Espoo, Finland). Y.P. acknowledges support ofDeutsche Forschungsgemeinschaft (DFG), Collaborative Re-search Centre SFB/TRR 173 “Spin+X.” G.S. acknowledgesfunding from MIUR PRIN Grant No. 20173B72NB and fromINFN17_nemesys project. R.v.L. likes to thank the Academyof Finland for support under Grant No. 317139. ...
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