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O: Fachverband Oberflächenphysik

O 56: Metal substrates: Epitaxy, growth and adsorbates

O 56.11: Talk

Thursday, March 26, 2009, 17:30–17:45, SCH A316

First-principles initial sticking coefficient for O₂ at Pd(100) — •Jörg Meyer and Karsten Reuter — Fritz-Haber-Institut, Faradayweg 4-6, D-14195 Berlin (Germany)

Although the first steps in the oxidation of metal surfaces are of fundamental importance e.g. in heterogeneous catalysis, first-principles investigations of the sticking behavior of oxygen molecules are still scarce and center on simple metals like Al(111) [1]. To address catalytically much more interesting transition metals, we apply a divide and conquer approach [2] to study sticking of oxygen on Pd(100): First, an analytical six dimensional potential energy surface (PES) is generated using a neural network to interpolate between several thousand energy data points obtained from density-functional theory in the generalized gradient approximation. After that, the initial sticking S₀ as a function of initial kinetic energy E₀ of the impinging oxygen molecules is calculated by evaluating a sufficiently large number of classical molecular dynamics trajectories on the previously constructed PES. We detail on technical aspects of the employed interpolation strategy, focussing on how symmetry of the (100) surface is exploited to reduce the necessary amount of input data and optimize the interpolation quality. In light of the good agreement of the obtained sticking curve S₀(E₀) with the sparse experimental data, we critically discuss the employed frozen-surface approximation and the importance of electronically non-adiabatic effects for this system.

[1] J. Behler et al., Phys. Rev. Lett. 94 (2005) 036104.

[2] A. Gross, Surf. Sci. Rep. 32 (1998) 291.