Quantitative analysis of bonding in 90° partial dislocation in diamond

The soliton model for motion of the 90° partial in silicon has provided an explanation for the large reduction in activation energy (1 eV) which occurs under prolonged exposure to an H plasma. Applying the same theoretical model to diamond yields a drop of 1.6 eV and puts dislocation motion into the realm of the possible. Here we examine with the `atoms in molecules' method the bonding in the local energy minima and saddle point structures involved in motion of the 90° partial. We find bonds with graphite character in the soliton, and, to a greater extent, in its saddle points for motion and kink pair nucleation. The presence of H does not suppress this character in any structure other than the kink pair, in which H is far less compressed. Furthermore we characterize the over-coordination of H in these structures.