A comparison of local-density approximations and classical potential calculations for the [001] Σ = 5 twist grain boundary showed that the complex structure which was observed in the defective grain boundary was caused by a simple electrostatic effect. Both methods predicted complex structures of octagons and squares. The electronic structure indicated that there were no states in the gap; thus suggesting that the so-called vacancies in the stable relaxed structure should be considered to be structural elements rather than true defects.

J.H.Harding, C.Noguera: Philosophical Magazine Letters, 1998, 77[6], 315-20