Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.77: Poster

Montag, 25. Februar 2008, 18:30–19:30, Poster F

Image-potential states at (001) surfaces of alkaline-earth metal oxides — •Björn Baumeier, Peter Krüger, and Johannes Pollmann — Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster

We present the results of a comparative ab initio study of the atomic and electronic structure of MgO, CaO, SrO and BaO and their relaxed (001) surfaces. Based on density functional theory, we use self-interaction-corrected pseudopotentials which permit a reliable description of electronic properties, in particular. The calculated bulk and surface geometric structures are consistent with well established literature data. The bulk electronic structure turns out to be in very good agreement with the results of quasiparticle calculations and experiment. Concerning surface electronic properties, the calculations reveal, in particular, that MgO(001), CaO(001) and SrO(001) exhibit negative electron affinity while BaO(001) does not. As a consequence, not only bound surface states which are localized at the surface occur in the former three cases but also a salient band of image-potential states appears in sections of the surface Brillouin zone which reside in vacuum in front of the surface. Such image-potential states do not arise at the BaO(001) surface.

The image-potential states at MgO(001) are compared to traditional image-potential states at Cu(001) and to traditional surface states at MgS(001), respectively. This exemplary comparision reveals details of the peculiar nature of the image-potential states at (001) surfaces of alkaline-earth metal oxides.