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O: Fachverband Oberflächenphysik

O 62: Surface chemical reactions II

O 62.7: Talk

Friday, March 27, 2009, 12:45–13:00, SCH A01

A new transferable method to calculate electronic excitations in adsorption on metal surfaces — •Matthias Timmer and Peter Kratzer — Fachbereich Physik - Theoretische Physik and Centre for Nanointegration (CeNIDE), Universitaet Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany

Non-adiabatic effects in adsorption on metal surfaces include the excitation of electrons and holes, which can be observed as chemicurrents. We present a new quantitative method on the basis of ground-state density-functional theory (DFT) to calculate these excitation probabilities. The method uses first-order time-dependent perturbation theory, which is implemented using the evaluation of matrix elements between Kohn-Sham states of the rate of change of the Kohn-Sham potential between subsequent static DFT calculations. We can access the excitation spectra directly. The method is applied to adsorption of atomic hydrogen isotopes on-top the Al(111) surface. Results can explain the experimental data for noble metal surfaces; in particular the observed isotope effect in H versus D adsorption is described. Moreover, the results are in quantitative agreement with computationally expensive calculations of the full dynamics within time-dependent DFT, with the notable exception of effects due to spin dynamics.

The method presented is simple enough to be applied to a wide class of adsorbates and surfaces, while at the same time allowing us to extract system-specific information. It can be implemented with reasonable effort within existing DFT codes [1].

[1] http://arXiv.org/abs/0810.5248