Kinetics versus thermodynamics in materials modeling: The case of the di-vacancy in iron |
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Authors: | F Djurabekova L Malerba RC Pasianot P Olsson K Nordlund |
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Institution: | 1. Structural Materials , Institute of Nuclear Materials Science, SCK?CEN , Boeretang 200, B-2400 Mol, Belgium;2. Helsinki Institute of Physics and Department of Physics , University of Helsinki , P.O. Box 43, FIN-00014, Finland flyura.djurabekova@helsinki.fi;4. Structural Materials , Institute of Nuclear Materials Science, SCK?CEN , Boeretang 200, B-2400 Mol, Belgium;5. Depto. Materiales , CAC-CNEA , Avda. Gral. Paz 1499, 1650 San Martín, Pcia. Buenos Aires, Argentina;6. CONICET , Avda. Rivadavia 1917, 1033 Buenos Aires, Argentina;7. Dept. MMC , EDF-R&8. D , Les Renardiéres, 77818 Moret-sur-Loing, France;9. Helsinki Institute of Physics and Department of Physics , University of Helsinki , P.O. Box 43, FIN-00014, Finland |
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Abstract: | Monte Carlo models are widely used for the study of microstructural and microchemical evolution of materials under irradiation. However, they often link explicitly the relevant activation energies to the energy difference between local equilibrium states. We provide a simple example (di-vacancy migration in iron) in which a rigorous activation energy calculation, by means of both empirical interatomic potentials and density functional theory methods, clearly shows that such a link is not granted, revealing a migration mechanism that a thermodynamics-linked activation energy model cannot predict. Such a mechanism is, however, fully consistent with thermodynamics. This example emphasizes the importance of basing Monte Carlo methods on models where the activation energies are rigorously calculated, rather than deduced from widespread heuristic equations. |
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Keywords: | Kinetic Monte Carlo di-vacancy vacancy cluster diffusion metals |
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