Atomistic simulation of crystal growth at the a < 1 0 0 > screw dislocation terminating at the {100} surface of MgO

We have performed the first atomistic simulations on the termination of scr ew dislocations at the surfaces of oxides. We have examined the structure a nd stability of the all a <1 0 0 > and 1/2a <1 1 0 > screw dislocations and the all a <0 0 0 > dislocation terminating at the {1 0 0} surface of MgO. These simulations show that the 1/2a <1 1 0 > is highly mobile leading to d islocation annihilation. Simulations where additional MgO units are attache d to a surface dominated by screw dislocations have been performed to learn more about their behaviour at the atomic scale during crystal growth. The initial binding is at the dislocation core with a second unit binding to th e first. The atoms rearrange as more molecules are added to give rise to gr owth of the step. (C) 2001 Elsevier Science B.V. All rights reserved.