Driving force and nucleation of supersonic dislocations

The answer to the question how fast a dislocation can travel through a crystal is at the heart of understanding the dynamics of mechanical deformation. Until recently it was believed that dislocations cannot surmount the sound barrier at the shear wave velocity since the energy of the dislocation has a singularity there. Using atomistic simulation we have then shown that dislocations can in fact move faster than the speed of sound if they are subjected to high shear stresses and if they are already created as supersonic dislocations at a strong stress concentration. In this manuscript the nucleation conditions are elaborated in more detail and the atomistic simulations are analysed further. To do so, the energetics and the forces on supersonic dislocations are studied in the framework of the Peierls model.