Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 13: Computational Materials Modelling III - Alloys
MM 13.1: Vortrag
Montag, 26. März 2012, 15:45–16:00, TC 006
Cluster expansions for kinetic Monte-Carlo simulations: towards time evolution with DFT accuracy — •Tobias C. Kerscher1,2, Martin Leitner1, Stefan Müller2, and Raimund Podloucky1 — 1University of Vienna, Institute of Physical Chemistry, Vienna, Austria — 2Hamburg University of Technology, Institute of Advanced Ceramics, Hamburg, Germany
We take first steps towards vacancy-mediated diffusion kinetics in aluminum alloys (e.g., Ni–Al and Fe–Al) by the combination of an ab initio based cluster expansion (CE) with Monte-Carlo simulations (MC). This method will incorporate many-body effects as well as variable transition barriers that depend on the structural environment of the jump, which is paramount for the calculation of MC jump rates according to transition state theory.
First, we present the energetics of selected transition paths in those Al alloys, determined by density functional theory (DFT) and the nudged-elastic-band method (NEB). Then, we show how the UNCLE code [1] and its kinetic Monte-Carlo algorithm will use a CE framework to include not only the energetics of all possible initial and final configurations of a transition, but also the correct configuration-dependent saddle points of the corresponding transition paths. Both contributions will be separately modeled by CEs based on ab initio input from DFT: the former by the energies of fully-relaxed input structures, the latter by the saddle points of the NEB method.
Work supported by FWF, Project number F4110 “ViCoM”.
[1] D. Lerch et al., Modelling Simul. Mater. Sci. Eng. 17 (2009), 055003