Atomic structure and energetics of constricted screw dislocations in copper

Atomistic simulations of cross slip of a dissociated screw dislocation have been performed. Shapes and energetics of different dislocation configurations relevant to cross slip in an f.c.c. metal (Cu) are determined. The minimum stress-free activation energy and activation length in the Friedel-Escaig cross-slip mechanism are determined. The simulations reveal a new energetically favourable configuration of a dissociated screw dislocation not previously considered. The importance of this configuration to surface nucleated cross slip is discussed.