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MM: Fachverband Metall- und Materialphysik
MM 7: Diffusion II
MM 7.1: Talk
Monday, February 25, 2008, 12:00–12:15, H 0111
Adaptive jump barrier height in Monte Carlo configuration kinetics. — •Martin Leitner1, Doris Vogtenhuber2, Wolfgang Pfeiler1, and Wolfgang Püschl1 — 1Dynamics of Condensed Systems, Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Wien — 2Computational Materials Science, Faculty of Physics, University of Vienna, Sensengasse 8, A-1090 Wien
In usual MC simulations of configuration kinetics atom jump probabilities are calculated from energies of the initial and/or final bound states of the moving atom, leaving aside the exact energy of the intermediate saddle point state. This energy may however be critically influenced by the local atomic environment. We propose a strategy to explicitly take account of this influence. The basis is ab initio calculation of representative jump paths in the framework of the nudged elastic band method. From these results, an influence function is derived which modifies the energy of the saddle point and therefore the effective jump barrier height as calculated from the initial and final states according to a cluster expansion scheme. The overall effect is demonstrated on the NiAl system.