Motion of dislocation kinks in a simple model crystal

To investigate the effects of lattice periodicity on kink motion, a molecular-dynamic simulation for a kink in a screw dislocation has been performed in a simple model lattice of diamond type. The Stillinger-Weber potential is assumed to act between atoms. Under applied stresses larger than 0.0027G, a long distance motion of a kink is possible, where G is the shear modulus. A moving kink emits lattice waves and loses its kinetic energy, which is compensated by the applied stress. The kink attains a terminal velocity after moving a few atomic distances. The kink velocity is not proportional to the applied stress, and exceeds the shear wave velocity when the applied stress is larger than 0.026G. The energy loss of the moving kink is one order of magnitude smaller than that of a moving straight dislocation and is about the same order of magnitude as the theoretical value of phonon-scattering mechanisms at room temperature.