Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.61: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

DFT calculations on influence of co-adsorbed Cl on the self-diffusion on Au(100) — •Mostafa Mesgar, Josef Anton, John A Keith, and Timo Jacob — Uni Ulm, Albert-Einstein-Allee 47

Adatom and vacancy diffusions play crucial roles in adsorption, desorption, crystal growth, and coarsening on metal surfaces. While several experimental and theoretical studies focused on the formation and diffusion of point defects on terraces, leading to a detailed understanding, much less is known about diffusion at steps and kink sites, even though this plays an important role in processes such as metal deposition and dissolution, Ostwald ripening, island and step fluctuations. Using ab initio density-functional theory, we investigated the self-diffusion behavior of adatoms on Au(100) surfaces with and without surface defects (e.g. steps, kinks, or vacancies) [1]. On terraced Au(100) surfaces, we find that exchange diffusion is the lowest energy mechanism while bridge diffusion is the next lowest. With surfaces in the presence of a perfect step edge, we find an even lower barrier for diffusion along the step-edge identifying that rearrangement of clusters will be faster than aggregation processes. This signifies that cluster edges might behave as catalysts. Afterwards we studied the influence of co-adsorbed Cl on the self-diffusion behavior, which turned out to have a drastic impact even on rather simple diffusion processes. Based on our present results the next aim is to perform large scale simulations, which then will provide macroscopic quantities readily comparable to experiments. [1] K. Pötting, T. Jacob, et al., High Performance Computing in Science and Engineering, Springer-Verlag GmBH, Heidelberg, Germany (2006).