Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 100: Surface Dynamics II
O 100.7: Vortrag
Freitag, 4. April 2014, 12:00–12:15, PHY C 213
Dynamics of O2 on Pd(100) – Unfreezing the surface — •Vanessa Jane Bukas1, Angela den Dunnen2, Jörg Meyer1, Ludo Juurlink2, and Karsten Reuter1 — 1Technische Universität München, Germany — 2Universiteit Leiden, The Netherlands
Despite its progress, state-of-the-art quantitative modeling in the field of gas-surface dynamics still faces considerable challenges when it comes to faithfully reproducing experimental data. We find such a discrepancy upon comparing measured sticking curves for O2 on Pd(100) with our first-principles results. Within the latter approach, we perform molecular dynamics simulations on a neural network interpolated potential derived from density-functional theory and accounting for all six molecular degrees of freedom [1]. Suspecting as source for the discrepancy the prevalent frozen surface approximation (FSA) underlying this approach, we extend our model to additionally include surface mobility in the form of a surface oscillator (SO), and a generalized langevin oscillator (GLO). While following the same dissociation mechanism, even a simple SO model significantly enhances the system’s reactivity and already yields remarkable agreement to experiment. Allowing for energy dissipation to the bulk within the GLO approach further reproduces molecular chemisorption at low surface temperatures as also suggested by electron energy loss spectroscopy [2]. Overall, our results thus underscore the importance of overcoming the FSA for adsorbates heavier than the prototypical H2.
[1] V. J. Bukas et al., Z. Phys. Chem., 227, 1523 (2013).
[2] C. Nyberg et al., Solid State Commun. 44, 251 (1982).