Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Metal subtrates: Adsorption of O and/or H
O 27.5: Vortrag
Dienstag, 23. März 2010, 11:30–11:45, H42
Dispersion effects in the dissociative adsorption of O2 on Al(111) — •Christian Carbogno1, Jörg Behler2, Karsten Reuter3,4, and Axel Groß1 — 1Universität Ulm, Germany — 2Ruhr-Universität Bochum, Germany — 3Fritz-Haber-Institut, Berlin, Germany — 4Technische Universität München, Germany
We have recently shown that the low sticking probability of thermal O2 molecules at Al(111) can be reproduced from first principles if spin selection rules are explicitly accounted for [1,2]. These hinder transitions from the initial O2 gas-phase triplet state to the singlet state of the adsorbed O atoms. In spite of the good agreement with the experimental sticking coefficient at normal incidence, its non-monotonic dependence on the incidence angle [3] is only partially reproduced by our calculations. A possible explanation for this discrepancy is the lack of dispersion forces in such a pure DFT approach. As a consequence, the calculated potential energy surfaces do not feature a physisorbed precursor state whose existence is assumed to lead to the observed non-monotonic dependence [3]. We inspect if and how various semi-empirical dispersion corrections (DFT-D) can compensate for this flaw in the description of this system. In addition, we discuss the implications of such corrections on the molecule-metal surface interaction.
[1] J. Behler et al., Phys. Rev. Lett. 94, 036104 (2005).
[2] C. Carbogno et al., Phys. Rev. Lett. 101, 096104 (2008).
[3] O. Weiße et al., J. Chem. Phys. 118 8010 (2003).