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Title: Calculation of the spectrum of quasiparticle electron excitations in organic molecular semiconductors

A quasiparticle electronic spectrum belongs to the characteristics of nanoobjects that are most important for applications. The following methods of calculating the electronic spectrum are analyzed: the Kohn-Sham equations of the density functional theory (DFT), the hybrid functional method, the GW approximation, and the Lehmann approximation used in the spectral representation of one-electron Green’s function. The results of these approaches are compared with the data of photoemission measurements of benzene, PTCDA, and phthalocyanine (CuPc, H{sub 2}Pc, FePc, PtPc) molecules, which are typical representatives of organic molecular semiconductors (OMS). This comparison demonstrates that the Kohn-Sham equations of DFT incorrectly reproduce the electronic spectrum of OMS. The hybrid functional method correctly describes the spectrum of the valence and conduction bands; however, the HOMO-LUMO gap width is significantly underestimated. The correct gap width is obtained in both the GW approximation and the Lehmann approach, and the total energy in this approach can be calculated in the local density approximation of DFT.
Authors:
 [1] ;  [2] ;  [1]
  1. Moscow State University (Russian Federation)
  2. Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
Publication Date:
OSTI Identifier:
22472214
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 120; Journal Issue: 6; Other Information: Copyright (c) 2015 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APPROXIMATIONS; BENZENE; COMPARATIVE EVALUATIONS; COPPER COMPOUNDS; DENSITY FUNCTIONAL METHOD; ELECTRONS; EXCITATION; GREEN FUNCTION; MOLECULES; ORGANIC SEMICONDUCTORS; PHOTOEMISSION; PHTHALOCYANINES; VALENCE