The core reconstruction of dislocations was investigated by using a linear-scaling density-matrix technique. The predominant dislocations (90º and 30º partials) were examined, and attention was focussed on the 90º case; with regard to single-period core reconstruction. In both cases, strongly reconstructed bonds were observed at the dislocation cores. Relatively low formation energies and high migration barriers were therefore generally associated with reconstructed (dangling bond-free) kinks. Complexes which consisted of a kink plus a reconstruction defect were found to be strongly bound in 30º partials, while the opposite was true in the case of 90º partials, where such complexes were only marginally stable at absolute zero; with very low dissociation barriers. In the case of 30º partials, the calculated formation energies and migration barriers of kinks compared favourably with experimental data. The results for kink energies on the 90º partial were consistent with an alternative double-period structure for the core of this dislocation.

R.W.Nunes, J.Bennetto, D.Vanderbilt: Physical Review B, 1998, 57[17], 10388-97