Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 59: Oxides and Insulators: Clean Surfaces
O 59.7: Vortrag
Donnerstag, 29. März 2007, 17:15–17:30, H41
Lattice Dynamics of RuO2: Bulk and (110) Surface — •Klaus-Peter Bohnen1, Rolf Heid1, and Omar de la Pena Seaman2 — 1Forschungszentrum Karlsruhe, Institut für Festkörperphysik — 2Department of Applied Physics, CINVESTAV-Mérida, Yucatán, Mexico
Although RuO2 has been studied as a prototype catalyst for CO oxidation no careful study of the lattice dynamics for this material has been presented so far. Using modern ab-initio methods we obtain the phonon dispersion and the generalized density of states (GDOS). Inelastic neutron scattering experiments allow for an experimental determination of the GDOS. In contrast to what is known from structural studies, we find that the local density approximation gives a much better description of the phonon spectrum than the generalized gradient corrected form. This is also consistent with Raman measurements. Besides the bulk we have also studied the lattice dynamics for the (110) surface. Unfortunately, no complete experimental phonon study of this surface has been carried out so far, however, our results are consistent with the available experimental information. These calculations allow for the first time for the determination of the bulk and surface part of the phononic contribution to the free energy, a quantity which is essential for the determination of thermodynamic properties.