Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 43: Clean surfaces III
O 43.9: Vortrag
Mittwoch, 28. März 2012, 12:30–12:45, MA 043
Atomistic modeling of electromechanical coupling at metal surfaces — •Anja Michl1,2, Jörg Weißmüller2,3, and Stefan Müller1 — 1Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany — 2Institute of Materials Mechanics, Helmholtz Zentrum Geesthacht, Geesthacht, Germany — 3Institute of Materials Physics, Hamburg University of Technology, Hamburg, Germany
Designing functional materials with well-defined catalytic properties requires understanding of the relation between surface structure and reactivity. Electrochemical experiments on pseudomorphic Pd monolayers have revealed the importance of strain for the catalytic activity of metal surfaces. Although the strain response of the electrode potential δ E/δ e has been measured for several materials, fundamental understanding of the underlying microscopic processes is far from complete. The variation of the potential of zero charge of an electrode surface in electrolyte is closely linked to the variation of the work function W in vacuum. In order to get further insight, we focus on simple s-p-bonded metals as they connect most readily to theory. We present density functional theory calculations of W for aluminum surfaces for varying tangential strain e which allow the determinination of δ W/δ e from first-principles. Interestingly, the response parameter is found to be positive in contrast to the negative values reported for e.g. Au experimentally and theoretically. We decompose the work function into a volume and a surface contribution and discuss the response of these contributions in the framework of the Jellium model.