Generalized stacking-fault energies for the basal plane of graphite were calculated, from first principles, for slip along 2 high-symmetry directions. The rhombohedral fault energy compared well with experiment, and its anisotropy of behavior was consistent with the dislocation network geometry. By combining these calculated fault energies with a modified Peierls-Nabarro model, the barrier to basal dislocation motion due to lattice friction was estimated. This was found to be extremely small. It was therefore concluded that dislocation network interaction and pinning, rather than the Peierls barrier, governed the practical shear strength of graphite. The shear strength was expected to tend to this lower limit at low dislocation densities or over small crystal regions.

Stacking Fault and Dislocation Glide on the Basal Plane of Graphite. R.H.Telling, M.I.Heggie: Philosophical Magazine Letters, 2003, 83[7], 411-21