Enhanced static approximation to the electron self-energy operator for efficient calculation of quasiparticle energies

Wei Kang and Mark S. Hybertsen
Phys. Rev. B 82, 195108 – Published 9 November 2010

Abstract

An enhanced static approximation for the electron self-energy operator is proposed for efficient calculation of quasiparticle energies. Analysis of the static Coulomb-hole screened-exchange (COHSEX) approximation originally proposed by Hedin shows that most of the error derives from the short-wavelength contributions of the assumed adiabatic accumulation of the Coulomb hole. A wave-vector-dependent correction factor can be incorporated as the basis for a new static approximation. This factor can be approximated by a single scaling function, determined from the homogeneous electron-gas model. The local field effect in real materials is captured by a simple ansatz based on symmetry consideration. As inherited from the COHSEX approximation, the new approximation presents a Hermitian self-energy operator and the summation over empty states is eliminated from the evaluation of the self-energy operator. Tests were conducted comparing the new approximation to GW calculations for diverse materials ranging from crystals, molecules, atoms and a carbon nanotube. The accuracy for the minimum gap is about 10% or better. Like in the COHSEX approximation, the occupied bandwidth is overestimated.

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  • Received 18 August 2010

DOI:https://doi.org/10.1103/PhysRevB.82.195108

©2010 American Physical Society

Authors & Affiliations

Wei Kang and Mark S. Hybertsen

  • Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA

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Issue

Vol. 82, Iss. 19 — 15 November 2010

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