The arrangement of atoms around an edge dislocation was calculated by using a variational method involving a central-force approximation. The pair-wise interaction between discrete atoms was represented by a Morse potential function. In calculating the complete dislocation, the atoms were not permitted to relax in a direction parallel to the dislocation line. This prevented dissociation. The core region was found to be neither hollow nor liquid-like. If the atoms were permitted to relax in a direction parallel to the dislocation line, the dislocation spontaneously dissociated into two Heidenreich-Shockley partials, and this process involved no activation energy. A stacking fault of infinite extent had an energy of 30mJ/m2 for the given potential and truncation used. Precautions had to be taken to ensure that the separation distance of the partials was the same as the distance given by elastic theory. Several different potential forms were used in the calculation of stacking-fault energy. The latter was found to be critically dependent upon the form of the interatomic potential. Using the Harrison pseudopotential for aluminum, the stacking-fault energy was approximately 250mJ/m2.

Energy and Atomic Configuration of Complete and Dissociated Dislocations. I. Edge Dislocation in an FCC Metal. R.M.J.Cotterill, M.Doyama: Physical Review, 1966, 145[2], 465-78