The University of Tokyo Department of Mechanical Engineering,Fracture Mechanics Laboratory.SAKAI & IZUMI group.

Research








TOP > Research

Nudged Elastic Band method for Crystal Dislocations

The plastic behavior of materials is governed by the nucleation and propagation of crystal dislocations. Dislocation nucleation can only be realistically studied by employing atomistic techniques. However, there is a need to bridge the time scale gap of 9 orders of magnitude between the second order at which dislocation nucleation experimentally occurs and the nanosecond order that is accessible to traditional atomistic methods. To bridge this time-scale gap, we are concerned with development and application of an activation path search methodology based on the Nudged Elastic Band method.
Fig. 1 shows the saddle point configurations (slip vector representation) corresponding to a series of stress values for homogeneous dislocation nucleation in Si. Fig. 2 shows the stress dependence of activation energy for homogeneous dislocation nucleation in Si as compared with homogeneous nucleation in Cu. We are therefore in a position to present relevant information not accessible to Molecular Dynamics on account of the long time scale involved in dislocation nucleation.

Fig. 1 Saddle point configurations (slip vector representation) corresponding to a series of stress values for homogeneous dislocation nucleation in Si

Fig. 2 Stress dependence of activation energy for homogeneous dislocation nucleation in Si (comparison with Cu)


Reference
[1] Satoshi Izumi, Sidney. Yip, “Dislocation Nucleation from a Sharp Corner in Silicon”, J. Appl. Phys. 104 (2008) 033513.
[2]Hasan Aftab Saeed, Satoshi Izumi, Shotaro Hara, Shinsuke Sakai: “Transition Pathway Analysis of Homogeneous Dislocation Nucleation in a Perfect Silicon Crystal”, Mater. Res. Soc. Symp. Proc. Volume 1224 (2010), 1224-FF05-14.








Copyright (C) 2002-2013 . Fracture Mechanics Laboratory, All rights reserved..