Molecular dynamics simulations were made of the a/2<110> screw dislocation by using quantum-mechanical Sutton-Chen many-body potentials. The core energy and structure were studied by using a quadrupolar dislocation system, with 3-dimensional periodic boundary conditions. The relaxed structures exhibited dissociation into 2 partials on {111} planes. The equilibrium separation distance between the 2 partials was 2.5nm. This was larger than that deduced from experimental data, due to the low stacking-fault energies predicted by the Sutton-Chen force field. The core energy of the a/2<110> screw dislocation was calculated to be 0.5eV/b. The motion and annihilation of opposite-sign dislocations were also studied. The dipole system was built up using 2 combinations of dissociation planes. One involved 2 dislocations which were dissociated on intersecting slip planes, while others were dissociated on parallel planes. Cross-slip, and the associated energy barriers, were also studied by using these simulations.

Large Scale Atomistic Simulations of Screw Dislocation Structure, Annihilation and Cross-Slip in FCC Ni. Y.Qi, A.Strachan, T.Cagin, W.A.Goddard: Materials Science and Engineering A, 2001, 309-310, 156-9