Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: Density functional theory and beyond for real materials III
O 65.2: Vortrag
Donnerstag, 25. März 2010, 10:45–11:00, H34
Unravelling the enigma of the F center in MgO with many-body perturbation theory — •Patrick Rinke1,2, Anderson Janotti2, Andre Schleife3, Emmanouil Kioupakis2, Claudia Roedl3, Friedhelm Bechstedt3, Chris G. Van de Walle2, and Matthias Scheffler1,2 — 1Fritz-Haber-Institut der MPG, 14195 Berlin, Germany — 2Materials Dep., University of California Santa Barbara, CA, USA — 3Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
The anion vacancy in bulk MgO (also called F- or color center) can probably be regarded as the classic intrinsic point defect in compound insulators. Its characterization has been impeded for decades by the fact that the neutral and the positively charged F-center (denoted F and F+, respectively) absorb at nearly identical energies [1]. To unravel this problem we apply a recently developed formalism that combines density functional theory (DFT) with many-body perturbation theory (MBPT) in the G0W0 approximation [2,3]. We find that this approach corrects the DFT formation energies in the local-density approximation (LDA) significantly. To describe the optical spectrum, however, it proves to be necessary to go one step further in the hierarchy of MBPT, i.e. solving the Bethe-Salpeter equation. After inclusion of the electron-hole and electron-phonon interaction we observe unprecedented agreement between the calculated and the experimental optical absorption spectra for the F and F+ center [1]. [1] L. A. Kappers, et al., Phys. Rev. B 1, 4151 (1970). [2] Hedström et al. Phys. Rev. Lett. 97, 226401 (2006). [3] P. Rinke, et al., Phys. Rev. Lett. 102, 026402 (2009).