The core structure of «001» dislocations in bcc metals

The core structure of dislocations with the Burgers vector a 001 in bcc lattices is studied using the generalized Peierls model and the eta-surfaces of the {110} planes recently calculated by Vitek et al . for Mo and Nb. In contrast with previous atomic simulations for dislocations on {100} planes it is found that the core region of an edge dislocation shows a dissociation and acquires a considerable screw component; hence it possesses a polarity. For a 001 screw dislocations no dissociation takes place.