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Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 6: Metal Substrates: Clean Surfaces

O 6.7: Talk

Monday, February 25, 2008, 12:45–13:00, MA 005

Efficient ab-initio based modelling of segregation profiles in metal alloys for arbitrary bulk concentrations — •Tobias Kerscher and Stefan Müller — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen

As shown recently [1], the combination of density functional theory (DFT) with cluster expansion methods and Monte-Carlo simulations is a powerful tool to model surface segregation in binary metal alloys. However, the predicted surface properties are then restricted to the in-plane lattice parameter defined by the bulk concentration of the alloy. Indeed, a change of the bulk concentration demands the re-calculation of all atomic configurations via DFT being the most time-consuming factor in the used approach. We will present a cluster-expansion Hamiltonian which provides universal and volume-corrected bulk energetics for all bulk concentrations, and simultaneously, minimizes the number of DFT calculation which have to be performed. This is demonstrated for the [100] direction of the bulk systems Pt25Rh75 and Pt50Rh50. Our results are in quantitative agreement with experimental measurements.
Supported by Deutsche Forschungs-Gemeinschaft

[1] S. Müller, M. Stöhr, O. Wieckhorst, Appl. Phys. A. 82, 415 (2006).

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