The formation energy of kink pairs in dissociated screw dislocations on the {111} planes of face-centered cubic lattices was studied, using Cu as an example. The 2 Shockley partials were represented by Peierls dislocations which were separated by a splitting width. The misfit energy in the glide plane was deduced from the γ-surface. The Peierls energy was derived by shifting the centre of the dislocation, and numerically summing the misfit energy at the position of the atom rows parallel to the dislocation line. There existed a number of stable equilibrium configurations, with different separations. If the separation of the partials remained constant as they moved, the periodicity of the Peierls potential was equal to the distance, a, between atom rows. However, when the separation between partials was allowed to vary, there existed minima in the potential at multiples of a/2. Normal kink pairs of height, a, could and, under certain conditions, fractional kink pairs with a height close to a/2 and having less than half of the formation energy of normal kink pairs.

Normal and Fractional Kink Pairs in Dissociated Dislocations. G.Schoeck: Philosophical Magazine A, 2002, 82[5], 1033-48