The origin of long-range correlated jumps observed in molecular-dynamics simulations of Brownian motion of interstitial clusters in irradiated crystalline materials was investigated. It was shown that the presence of long jumps was associated with low thermal friction experienced by a cluster propagating through the crystal lattice in the presence of thermal fluctuations. Using the equation for the friction coefficient, the length of ballistic trajectories of clusters ejected from high-energy cascades was estimated.

Thermal Friction and Brownian Motion of Interstitial Defects in Irradiated Materials. S.L.Dudarev: Journal of Nuclear Materials, 2002, 307-311[2], 881-5