Crowdion mobility and self-focusing in 3D and 2D nickel

Crowdion is a special configuration created by an interstitial atom that can propagate in a close packed direction as a quasi-particle. Motion of crowdions can contribute to material transport during cascade-producing irradiation and also during plastic deformation. Crowdions can move only at relatively high velocity sufficient to overcome the Peierls–Nabarro potential (mobility), but their stable (self-focusing) motion is possible for sufficiently small velocities when the effective radius of colliding atoms is sufficiently large. By means of molecular dynamics simulation we find that in 3D and 2D nickel at zero temperature both mobility and stability criteria can be met for a crowdion in a window if its propagation velocity.