  Basal slip of a screw dislocations in hexagonal closed-packed titanium is
investigated with ab initio calculations. We show that a basal dissociation is
highly unstable and reconfigures to other structures dissociated in a first
order pyramidal plane. The obtained mechanism for basal slip corresponds to the
migration of the partial dislocations and of the associated stacking fault
ribbon in a direction perpendicular to the dissocia-tion plane. Presented
results indicate that both basal and pyramidal slip will operate through the
Peierls mechanism of double-kink nucleation and will be equally active at high
enough temperature.
