The concerted exchange mechanism is currently the only viable candidate, for atomic exchange, that does not involve intrinsic lattice defects. In order to evaluate its contribution to Si self-diffusion, the entropy which was associated with concerted exchange was calculated. Full relaxation of the energy surface was included via an interatomic potential. The predominant contribution of vibrational modes was taken into account via the harmonic approximation. This gave an entropy of 6.3k; which agreed with the observed range of experimental results. It was concluded that the concerted exchange mechanism was a significant contributor to self-diffusion in Si.

E.Kaxiras, K.C.Pandey: Physical Review B, 1993, 47[3], 1659-62