Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Oxides and Insulators: Epitaxy and Growth
O 33.6: Vortrag
Dienstag, 27. März 2007, 17:00–17:15, H41
Electronic structure and quasiparticle calculations of molecules on thin epitaxial films - a DFT and GW study — •Christoph Freysoldt, Patrick Rinke, and Matthias Scheffler — Fritz-Haber-Institut der MPG, Berlin, Germany
To study insulator surfaces with surface-science techniques that require conducting samples such as photoelectron spectroscopy or STM epitaxial films are often employed. However, the difference in the dielectric properties between the film and the substrate intrduces additional polarization effects that modify the electronic states of the film and of molecules adsorbed on it. Here, we present G0W0 quasiparticle calculations that incorporate these effects in a natural way, for the electronic structure of molecule/film/substrate system, using NaCl/Ge(001) as a prototypical insulator/semiconductor interface and CO as a model adsorbate. The atomic structure of the NaCl/Ge(001) in interface – so far unknown from experiment – is determined using density-functional theory. We observe that the quasiparticle gap of CO adsorbed on the NaCl film varies as a function of the film thickness. The dielectric response of the substrate also introduces a z-dependence of the quasiparticle corrections within the NaCl film, which then differ by up to 0.6 eV between the Ge-interface and the surface. In experiments either metallic substrates are used or the semiconducting substrates are strongly doped to increase their conductivity. We expect that the effects reported here will be even more pronounced for these substrates due to their larger polarizability.