Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 32: Metal Substrates I
O 32.4: Vortrag
Dienstag, 12. März 2013, 11:15–11:30, H42
Electromechanical coupling coefficients of sp-bonded metals from first principles — •Anja Michl1,2, Jörg Weissmüller1,3, and Stefan Müller2 — 1Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany — 2Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany — 3Institute of Materials Physics and Technology, Hamburg University of Technology, Hamburg, Germany
Coupling between mechanical stress or strain of a surface and its electronic properties is relevant for a range of applications from sensors and actuators to heterogeneous catalysis. In experiment, coupling coefficients are determined via electrochemical experiments, e.g. by measuring the change in electrode potential upon applying tangential strain e to the electrode surface. Theoretically, this coupling strength is obtained as the response of the electronic work function W to strain. Thus, we calculate strain response parameters dW/de for several sp-bonded metals from first principles using density functional theory. We find an increasing trend for the coupling coefficients with increasing number of valence electrons. For aluminum the sign is inverted leading to abnormal positive response parameters for all orientations considered. Due to the simple sp-bonded electronic structure of the investigated metals the homogeneous electron gas represents a suitable model system. Based on an analysis of the surface and volume contributions of the work function within the framework of this jellium model, we propose the unusual positive sign to be related to the high electron density of aluminum.