Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 24: Postersitzung (Epitaxie und Wachstum, Oxide und Isolatoren, Elektronische Struktur, Oberfl
ächenreaktionen, Adsorption an Oberfl
ächen, Organische Dünnschichten)

O 24.45: Poster

Mittwoch, 26. März 2003, 14:30–17:30, P1

Nonadiabatic processes during adsorption of H on Al(111) — •M. Lindenblatt and E. Pehlke — Fachbereich Physik, Universität Essen

Part of the energy released by chemical reactions on metal surfaces is transferred into electron-hole pairs; this was demonstrated experimentally by the occurence of chemocurrents [1]. We investigate two non-adiabatic processes for a model system, the chemisorption of H on the Al(111) surface. First, the loss of spin polarisation of the incoming hydrogen atom at a distance of about 1.5 Å from its equilibrium position has been calculated ab initio. The lifetime of the relevant spin states has been estimated from their energy width. This yields an estimate for the possible nonadiabaticity of this process. Second, to simulate electronic friction, the solution of the time-dependent Kohn-Sham equations is implemented into the fhi96md [2] electronic-structure package, with the exchange-correlation functional in the adiabatic approximation. In the molecular-dynamics simulation the system can depart from its Born-Oppenheimer surface. First results for different trajectories of H/Al(111) are presented.

[1] H. Nienhaus, Surf. Sci Rep. 45, 1 (2002).

[2] M. Bockstedte, A. Kley, J. Neugebauer, M. Scheffler, Comp. Phys. Commun. 107, 187 (1997).