It was recalled that thermally activated Brownian motion of interstitial defects was one of the factors which drove the evolution of the microstructures of crystalline metals under irradiation. In the limit of relatively small system size, the motion of defects could be followed at the atomistic scale by using molecular dynamics. Understanding the kinetics of evolution of the microstructures required an investigation of how defects migrated and interacted on a scale which was substantially greater than that treatable by molecular dynamics. It was shown here how mobile interstitial defects could be described by quasi-particle solutions to the multi-string Frenkel-Kontorova model, which proved the equivalence of the crowdion and glissile dislocation loop representations of small interstitial clusters. An exact solution to the multi-string Frenkel-Kontorova model was found for the case of an infinite straight edge dislocation. This solution illustrated the fundamental link between the concept of a crowdion and of a dislocation in a crystalline material.

Coherent Motion of Interstitial Defects in a Crystalline Material. S.L.Dudarev: Philosophical Magazine, 2003, 83[31], 3577-97