The nudged elastic band method was used to calculate the energetics of the kink-pair mechanism for the motion of ½<111> screw dislocation cores in body-centered cubic Fe. At low applied stresses, the critical event was found to be expansion of the kink-pair

while, at high applied stresses, it was nucleation of the kink-pair that was rate-controlling. The activation energy for the motion was found to decrease with increasing stress, but the predicted flow stress was about 3 times the experimental value at all temperatures.

Atomistic Simulation of Energetics of Motion of Screw Dislocations in BCC Fe at Finite Temperatures

. A.H.W.Ngan, M.Wen: Computational Materials Science, 2002, 23[1-4], 139-45