Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 33: Symposium Materials Modelling II
MM 33.1: Fachvortrag
Donnerstag, 30. März 2006, 14:45–15:15, IFW A
The first coarse-graining step in alloy theory from the electronic to the atomic level: Transferable potentials and cluster-expansion method — •Manfred Fähnle1, Ralf Drautz1,2, Alessandro Diaz-Ortiz1, Frank Lechermann1,3, Reinhard Singer1, and Helmut Dosch1 — 1MPI Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart — 2Department of Materials, University of Oxford, Oxford, OX1 3PH, UK — 3Ecole Polytechnique, CPHT, Palaiseau, F-91128, France
For the comprehensive description of the properties of alloys and compounds a combination of theories on various scales is required. On the most fundamental scale, i.e., the electronic scale, the density functional electron theory is able to yield reliable information for single systems, but it cannot scan a very large variety of competing structures in order to determine the ground-state structures or the finite-temperature phase diagrams in multi-component systems. To do this, a first coarse-graining step from the electronic to the atomic scale is required. It is shown [1] that this can be achieved, in principle whithout loosing the accuracy of the ab-initio calculations, by means of transferable potentials and by the cluster-expansion method (CE). The recently developed methods to construct terminated but well-converged CEs are discussed, as well as extensions of the CE method to magnetic degrees of freedom. The power and the remaining limitations of the presently established versions of the CE method are demonstrated for a variety of technologically interesting systems.
[1] R. Drautz et al., J. Phys.: Cond. Matter 16, 3843 (2004).