1307.3848 (Mark R. Gilbert et al.)

Degenerate transition pathways for screw dislocations: implications for
migration    [PDF]

Mark R. Gilbert, Sergei L. Dudarev, Peter M. Derlet

In body-centred-cubic (bcc) metals migrating 1/2<111> screw dislocations experience a periodic energy landscape with a triangular symmetry. Atomistic simulations, such as those performed using the nudged-elastic-band (NEB) method, generally predict a transition-pathway energy-barrier with a double-hump; contradicting Ab Initio findings. Examining the trajectories predicted by NEB for a particle in a Peierls energy landscape representative of that obtained for a screw dislocation, reveals an unphysical anomaly caused by the occurrence of monkey saddles in the landscape. The implications for motion of screws with and without stress are discussed.

View original: http://arxiv.org/abs/1307.3848