Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 74: Metal Substrates: Adsorption of O and/or H
O 74.6: Talk
Thursday, February 28, 2008, 16:15–16:30, MA 141
Hindered Spin-Transitions in the Dissociative Adsorption of O2 on Al(111) — •Christian Carbogno1, Jörg Behler2, Axel Groß1, and Karsten Reuter3 — 1Institut für Theoretische Chemie, Universität Ulm, Germany — 2Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Germany — 3Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
The low sticking probability for thermal O2 molecules at Al(111) has recently been related to spin selection rules, which hinder transitions from the initial O2 gas-phase triplet state to the singlet state of the adsorbed O atoms [1]. A constrained DFT approach was employed to compute potential energy surfaces (PESs) of O2 in different spin-configurations from the surface, and the experimental sticking probability was qualitatively reproduced when restricting the O2 molecule to motion on the spin-triplet PES only. Here, we extend these studies by considering the dissociation dynamics on multiple spin PESs, allowing transitions between them within Tully’s fewest-switches algorithm as recently implemented [2]. The required non-adiabatic coupling elements have been derived in an ab initio fashion from the comparison between adiabatic and constrained-DFT PESs. Within this framework we obtain both good agreement with experiment for the fundamental features of the system as well as deeper insight into more peculiar characteristics of the dynamics. Based on our results, we propose experiments which can be used for the validation of our approach.
[1] J. Behler et al., Phys. Rev. Lett. 94, 036104 (2005).
[2] C. Bach et al., Israel J. Chem. 45, 46 (2005).