Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic I

O 55.11: Talk

Wednesday, April 2, 2014, 19:00–19:15, TRE Phy

Ab-initio quantum dynamics simulation of photo-induced molecular switching: Azobenzene on coinage metals — •Reinhard J. Maurer and Karsten Reuter — Department Chemie, Technische Universität München, Germany

The constant pursuit towards further miniaturization of electronic devices slowly reaches the point where individual molecules may serve as the main functional units. Unfortunately, more often than not, an inherent molecular function is quenched by overly strong coupling to the environment; a permanent danger, specifically in the case of metal surface adsorption. Nevertheless, metal surface adsorption may also introduce new functionality, such as in the case of photo-induced molecular switching of tetra-tert-butyl-functionalized Azobenzene (TBA) on Au(111). In this work we attempt a full ab-initio description of the explicit nuclear and electronic dynamics to analyze a novel substrate-mediated process that was suggested for this system [1]. The immense system size and a continuum of electronic states demand an effective modelling approach explicitly accounting only for the most important degrees of freedom. Employing an efficient density-functional theory based ΔSCF approach [2] we construct and analyze the involved excited-state potential energy surfaces (PESs), and establish a mixed-quantum classical dynamics simulation. A particular focus is the effect of the image-charge induced changes on the excited-state PESs and the excited-state lifetime- and temperature-dependence of the quantum yield. [1] Wolf, Tegeder, Surf. Sci. 603, 1506–1517 (2009); [2] Maurer, Reuter, J. Chem. Phys. 139, 014708 (2013)