The mobility of self-interstitials was studied by using molecular dynamics and molecular statics simulations, and Ackland’s many-body inter-atomic potential. The basal crowdion configuration was found to be the ground state. Four types of diffusion jumps could be identified via molecular statics, in-plane in-line, in-plane off-line, out-of-plane in-line and out-of-plane off-line. The in-plane migration was dominated by 1-dimensional crowdion motion along the [11▪0] directions, interrupted from time to time by off-line or out-of-plane jumps. Based on the molecular statics results, the activation energies and pre-exponentials for the diffusion processes were determined by fits to the Arrhenius plots of Dc and Da. The diffusional anisotropy factor Dc/Da was also obtained, and compared well with experimental results. The mean frequency of each type of jumps was then found using Monte Carlo simulation, and was reported as a function of temperature. The mean lifetime and mean free path of the 1-dimensional mobility were then obtained. The 1-D mean free path was found to be unimportant for the sink separations which were involved in normal irradiation damage.

Low-Dimensional Self-Interstitial Diffusion in Zr. C.H.Woo, H.Huang, W.J.Zhu: Applied Physics A, 2003, 76[1], 101-6