Quasiparticle energies for large molecules: A tight-binding-based Green's-function approach
- Department of Theoretical Physics, University of Paderborn, D-33098 Paderborn (Germany)
- International University of Bremen, School of Engineering and Science, P.O. Box 750561, D-28725 Bremen (Germany)
- National Nanotechnology Laboratories of INFM, Universita di Lecce, Distretto Tecnologico, Via Arnesano, 73100 Lecce (Italy)
- INFM and Department of Electronic Engineering, University of Rome 'Tor Vergata', 00133 Rome (Italy)
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 (C{sub 4n+2}H{sub 2n+4}) up to n=30.
- OSTI ID:
- 20650075
- Journal Information:
- Physical Review. A, Vol. 71, Issue 2; Other Information: DOI: 10.1103/PhysRevA.71.022508; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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