Parquet approximation for molecules: Spectrum and optical conductivity of the Pariser-Parr-Pople model

P. Pudleiner, P. Thunström, A. Valli, A. Kauch, G. Li, K. Held

Publikation: Beitrag in einer FachzeitschriftArtikel

Abstract

We study a simple model system for the conjugated π bonds in benzene, the Pariser-Parr-Pople (PPP) model, within the parquet approximation (PA), exemplifying the prospects of the PA for molecules. Advantages of the PA are its polynomial scaling with the number of orbitals, and the natural calculation of one- and two-particle spectral functions as well as of response and correlation functions. We find large differences in the electronic correlations in the PPP model compared to a Hubbard model with only local interactions. The quasiparticle renormalization (or mass enhancement) is much weaker in the PPP than in the Hubbard model, but the static part of the self-energy enhances the band gap of the former. Furthermore, the vertex corrections to the optical conductivity are much more important in the PPP model. Because nonlocal interactions strongly alter the self-energy, we conclude that the PA is more suitable for calculating conjugated π bonds in molecules than single site dynamical mean-field theory.

Originalspracheenglisch
Aufsatznummer125111
FachzeitschriftPhysical Review B
Jahrgang99
Ausgabenummer12
DOIs
PublikationsstatusVeröffentlicht - 11 Mär 2019

ASJC Scopus subject areas

  • !!Electronic, Optical and Magnetic Materials
  • !!Condensed Matter Physics

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