Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Density functional theory and beyond for real materials III

O 65.6: Vortrag

Donnerstag, 25. März 2010, 11:45–12:00, H34

Reliable Kohn-Sham eigenvalues and self-interaction: a study on organic semiconductors — •Thomas Körzdörfer and Stephan Kümmel — Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany

Photoelectron spectroscopy is an important tool for investigating organic semiconductor materials such as PTCDA and NTCDA. Kohn-Sham (KS) eigenvalues obtained from density functional theory are frequently used as a tool to facilitate the interpretation of the measured spectra. So far, however, it was difficult to predict when the spectrum of occupied KS eigenvalues obtained from commonly used (semi-)local functionals bears physical relevance and when not. Clearly, this considerably limits the practical usefulness of the approach and triggers the need for an easy criterion which can serve as a warning against possible misinterpretation of the eigenvalue spectrum. In this work, we demonstrate that such a criterion can be based on evaluating each orbital's self-interaction error [1]. With PTCDA and NTCDA serving as examples it is shown that the spatial structure of the highest lying KS orbitals is decisive for the physical reliability of the eigenvalue spectrum obtained from (semi-)local functionals. We further demonstrate that a recently introduced generalized optimized effective potential scheme [2] that is based on the self-interaction correction of Perdew and Zunger leads to reliable eigenvalues also in difficult cases such as PTCDA where (semi-)local functionals fail.

[1] T. Körzdörfer, et al., Phys. Rev. B 79, 201205(R) (2009).

[2] T. Körzdörfer, et al., J. Chem. Phys. 129, 014110 (2008).