Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 47: Rastersondentechniken III

O 47.8: Vortrag

Dienstag, 8. März 2005, 17:30–17:45, TU EB202

Calculation of STM images of defect and adsorbate structures on the ZnO(1010) surface — •Roman Kovacik, Bernd Meyer, and Dominik Marx — Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany

The interpretation of scanning tunneling microscopy (STM) experiments is often difficult since STM images are not a direct probe of the atomic structure of a surface but of its electronic properties. To determine STM images from electronic structure calculations we have implemented the two most common methods, the Tersoff–Haman approach and the evaluation of Bardeens tunneling formula, into the density–functional based Car–Parrinello Molecular Dynamics (CPMD) code. As first applications we have calculated STM images together with selected I(V)–profiles (scanning tunneling spectroscopy – STS) for (i) the clean ZnO(1010) surface, (ii) the surface with oxygen, zinc and ZnO vacancies and (iii) the adsorbate–covered surface considering different coverages of water molecules. Characteristic differences between the Tersoff–Haman and the Bardeen approach will be discussed, and the calculations will be compared to recent experimental results.