Berlin 2008 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
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).