Regensburg 2004 – wissenschaftliches Programm
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M: Metallphysik
M 5: Elektronische Eigenschaften
M 5.1: Vortrag
Montag, 8. März 2004, 11:45–12:00, H4
Perfectly transferable many-body potentials and related generalized cluster expansions not confined to lattices — •Manfred Fähnle1, Ralf Drautz1, and Juan M. Sanchez2 — 1MPI für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany — 2Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712
There are two main streams for the parametrized representation of the energy of a system of atoms, the expansion into many-body potentials (which focusses on the positional degrees of freedom) and the conventional cluster-expansion technique [1] (which focusses on the ordering degrees of freedom in multicomponent lattice systems). To accelerate the convergence of the many-body expansion, often empirical effective and environment-dependent many-body potentials with fitting parameters are used which have the disadvantage that they are accurate only for configurations close to certain reference configurations. We demonstrate how perfectly transferable many-body potentials can be generated by ab-initio total energy calculations. The so-defined many-body potentials can be used to compare empirical energy parametrizations on the basis of the behaviour of their respective potential expansion. It is shown how the techniques of the many-body expansion and of the conventional cluster-expansion can be merged to a generalized cluster-expansion not confined to lattices.
[1] J. M. Sanchez et al., Physica 128A, 334 (1984).