Tight-binding  ab initio  and classical calculations were performed for ½<110> edge dislocation dipoles, with separations of 0.75 to 2.29nm, in unit cells which comprised between 32 and 288 atoms. The calculations revealed states that were associated with cores that were relatively deep in the band gap (about 0.2eV), in spite of the absence of dangling bonds. Shifts in the electronic states depended markedly upon the separation, and were correlated with a concentration of strain in the cores as the dislocations became more isolated. The strain energies exhibited a logarithmic dependence, upon the separation, which was consistent with a linear elasticity for all system sizes.

F.Liu, M.Mostoller, V.Milman, M.F.Chisholm, T.Kaplan: Physical Review B, 1995, 51[23], 17192-5