The first ab initio density-functional study of the strain field and Peierls stress of isolated <111> screw dislocations in body-centered cubic Ta was reported. The local dislocation strain field was self-consistently coupled to the long-range elastic field by using a flexible boundary condition method. This reduced the mesoscopic atomistic calculation to one involving only degrees of freedom near to the dislocation core. The predicted equilibrium core for Mo was significantly different to previous atomistic results, and the Peierls stress exhibited significant non-Schmid behavior; as expected for body-centered cubic metals.

Flexible ab initio Boundary Conditions - Simulating Isolated Dislocations in BCC Mo and Ta. C.Woodward, S.I.Rao: Physical Review Letters, 2002, 88[21], 216402 (4pp)