Quasiparticle energies for large molecules: A tight-binding-based Green’s-function approach

T. A. Niehaus, M. Rohlfing, F. Della Sala, A. Di Carlo, and Th. Frauenheim
Phys. Rev. A 71, 022508 – Published 22 February 2005

Abstract

We present a tight-binding approach for the calculation of quasiparticle energy levels in confined systems such as molecules. The method is based on Hedin’s GW approximation, in which the self-energy is given as the product of the Green’s function (G) and the screened Coulomb interaction (W). Key quantities in the GW formalism such as the microscopic dielectric function are expressed in a minimal basis of spherically averaged atomic orbitals. All necessary integrals are either precalculated or approximated without resorting to empirical data. The method is validated against first-principles results for benzene and anthracene, where good agreement is found for levels close to the frontier orbitals. Further, the size dependence of the quasiparticle gap is studied for conformers of the polyacenes (C4n+2H2n+4) up to n=30.

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  • Received 1 November 2004

DOI:https://doi.org/10.1103/PhysRevA.71.022508

©2005 American Physical Society

Authors & Affiliations

T. A. Niehaus1,2, M. Rohlfing3, F. Della Sala4, A. Di Carlo5, and Th. Frauenheim1

  • 1Department of Theoretical Physics, University of Paderborn, D-33098 Paderborn, Germany
  • 2German Cancer Research Center, Department of Molecular Biophysics, D-69120 Heidelberg, Germany
  • 3International University of Bremen, School of Engineering & Science, P.O. Box 750561, D-28725 Bremen, Germany
  • 4National Nanotechnology Laboratories of INFM, Universitá di Lecce, Distretto Tecnologico, Via Arnesano, 73100 Lecce, Italy
  • 5INFM and Department of Electronic Engineering, University of Rome “Tor Vergata,” 00133 Rome, Italy

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Issue

Vol. 71, Iss. 2 — February 2005

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