Ab initiocalculation of Peierls stress in silicon

The Peierls stress of a straight screw dislocation in Si has been studied by an ab initio molecular dynamics simulation. The generalized stacking fault energy in Si can no longer be the continuous function of displacement of the slip plane with structural relaxation. Then the Peierls-Nabarro theory fails to describe properties of the dislocation core, such as the Peierls stress. Direct simulation of the slip dynamics of dislocations has also been performed and the Peierls stress is derived without any artificial modeling of a dislocation core with an excellent agreement with experimental results. The effect of the Peierls potential on the slip dynamics of dislocations is also discussed.