Boundary conditions for dislocation core structure studies: application to the 90° partial dislocation in silicon

The effects of boundary conditions on studies of dislocation cores are examined, using the 90° partial dislocation in Si as an illustration. The relative stability of two possible reconstructions of the core are explored using periodic supercell calculations and cylindrical boundary conditions and the results compared. It is argued that the stable core structure depends systematically on the stress field experienced by the dislocation, and that this dependence can be quantified effectively using a combination of periodic supercells and elasticity theory.