Saddle point energies from ab initio jump profiles in MC simulation of order kinetics in intermetallics.

Author(s)

Martin Leitner, Doris Vogtenhuber, Wolfgang Pfeiler, Wolfgang Püschl

Abstract

Kinetic Monte Carlo (KMC) simulation is a valuable tool to investigate configu-ration changes in intermetallic compounds. The elementary process is the jump of an atomfrom a lattice site to a neighboring vacancy. In classical transition state theory the jump ratecontains the energy difference between the original equilibrium state and the saddle point (=transition) state. In traditional KMC the saddle point has mostly received rather careless treat-ment, setting it constant or relating it to the type of jumping atom. In the present work, saddlepoint heights were considered explicitly. Taking L12 ordered Ni3Al as an example, jump energyprofiles for various atom environments were calculated ab initio in relaxed configurations ofa 3x3x3 supercell, employing the Nudged Elastic Band method where necessary. From theseresults, effective ’pure’ saddle point heights were extracted. To show the effect on kinetics,simulations of order-order transitions were done with jump probabilities based on these results.When compared to the old assumption of constant saddle point heights, both overall kineticsand detailed jump statistics result considerably changed.

Organisation(s)

Department of Physical Chemistry, Dynamics of Condensed Systems, Computational Materials Physics

Journal

Solid State Phenomena (Diffusion and defect data B)

Volume

172-174

Pages

1022-1027

No. of pages

6

ISSN

1012-0394

DOI

https://doi.org/10.4028/www.scientific.net/SSP.172-174.1022

Publication date

2011

Peer reviewed

Yes

Austrian Fields of Science 2012

103015 Condensed matter, 103018 Materials physics

Portal url

https://ucris.univie.ac.at/portal/en/publications/saddle-point-energies-from-ab-initio-jump-profiles-in-mc-simulation-of-order-kinetics-in-intermetallics(3652cddd-8992-48af-baf0-1889a9a8dca5).html