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

Journal Article · Mon Jun 15 04:00:00 EDT 2015 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S1063776115050210· OSTI ID:22472214

Uspenskii, Yu. A. ^[1]; Khokhlov, D. R. ^[2]

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1. Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
2. Moscow State University (Russian Federation)

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.

• OSTI ID: 22472214
• Journal Information: Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 6 Vol. 120; ISSN JTPHES; ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

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