Extensive first-principles calculations were made of the formation energies and migration barriers of elementary defects in graphite, as well as for the activation energy of atomic exchange. The calculations showed that then long-held view that atomic diffusion in graphite occurred via the direct-exchange mechanism, was incorrect, although more complicated exchange processes have not been ruled out. It was found that diffusion in graphite was most likely mediated by vacancies with an activation energy which was lower than that of the interstitial and the direct-exchange mechanisms, and was in reasonable agreement with experiment.

Energetics of Defects and Diffusion Mechanisms in Graphite. Kaxiras, E., Pandey, K.C.: Physical Review Letters, 1988, 61[23], 2693-6