Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Metal substrates: Adsorption of organic / bio molecules IV

O 37.3: Talk

Tuesday, March 23, 2010, 15:30–15:45, H36

DFT study of PTCDA on Ag(111) including a STM tip — •Andreas Greuling, Marcin Kaczmarski, and Michael Rohlfing — Universität Osnabrück, Fachbereich Physik, Barbarastraße 7, 49069 Osnabrück

Any progress in the field of molecular electronics requires a detailed knowledge of conduction through molecules. As a prerequisite, detailed knowledge of the geometrical structure of a model system like the system 'PTCDA on Ag(111) probed with a STM tip' is of big importance. In experiment it is possible to peel the PTCDA from the surface by using a STM tip above a corner oxygen atom. Furthermore, the molecule flips from the surface to the tip and back under certain tip-surface distance and voltage conditions. Here, we investigate these mechanisms by employing ab initio calculations applying the widely used SIESTA code. Using Density Functional Theory (DFT) in the Local Density Approximation (LDA) we present calculated geometries for the process of peeling of the molecule. Additionally we show tip-surface interaction potentials also considering the influence of a homogen electrical field.