Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 24: Adsorption III
O 24.6: Vortrag
Dienstag, 28. März 2006, 17:00–17:15, TRE Phys
Hydrogen adsorption dynamics on clean and precovered Pd(100) surfaces from first principles — •Axel Groß — Department of Theoretical Chemistry, University of Ulm, 89069 Ulm/Germany
Ab initio molecular dynamics simulations based on density functional theory (DFT) calculations have been performed to study the adsorption of H2 on clean and hydrogen-covered Pd(100) surfaces. In the simulations, the surface atoms have been treated dynamically thus allowing a realistic description of the energy transfer from the impinging molecules to the substrate. On the clean surface, the sticking probability is hardly influenced by the recoil of the metal substrate atoms because of the large mass mismatch. However, if the H2 molecules impinge on a hydrogen-covered surfaces with coverages ΘH ≤ 0.5, the recoil of the preadsorbed hydrogen atoms causes an significant enhancement of the sticking probability. This leads to a H2 sticking probability which is much larger than what one would expect from a simple site-blocking picture. For higher coverages, the repulsive interaction between the hydrogen atoms has to be taken into account which partially counterbalances the promoting effect of the recoil.