Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 56: Oxide Surfaces I
O 56.12: Vortrag
Mittwoch, 13. März 2013, 18:45–19:00, H45
Ab initio study of low-coordinated sites on MgO(100) using hybrid functionals — •Philipp Auburger1, Manuel Kolb1,2, and Michel Bockstedte1 — 1Theoretische Festkörperphysik, FAU Erlangen-Nürnberg, Erlangen, Germany — 2Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
Low-coordinated surface sites, such as surface oxygen vacancies and step edges are reactive centers at the MgO(100) surface. To unravel their role in chemical reactions and as optical recombination centers, it is pivotal to understand their electronic states. Density functional theory together with the (semi-)local exchange-correlation functionals, however, underestimate the band gap of metal oxides by a large margin. Hybrid functionals like the HSE06, are known1 to improve the description of metal oxides considerably. Here we investigate surface color centers on the MgO(100) surface including the step edges, oxygen vacancy on the surface and at step edges, as well as kink sites using the DFT-HSE06 approach and a slab model. This enables a proper description of defect and dispersing shallow step edge states. For both states we find large corrections to values obtained with standard functionals. In addition, the calculations reveal a negative electron affinity in agreement with GW calculations.2 We compare our results with recent STS-experiments on color centers at MgO-films.3
[1] G. Pacchioni, J. Chem. Phys. 128, 182505 (2008).
[2] M. Rohlfing , et al, Phys. Rev. Lett. 91, 2568021 (2003).
[3] M. Sterrer et al, J Phys. Chem.B 110, 46-49 (2006).