The general features of the atomic and electronic structures of grain boundaries were investigated by making tight-binding calculations of various coincidence tilt and twist boundaries. By comparing tilt and twist boundaries, and examining the effects of rigid-body translations, it was shown that the predominant feature of stable boundary structures was the formation of stable structural units that consisted of atomic rings within small bond distortions. By analyzing the effects of local structural disorder upon the electronic structure, it was concluded that distorted or weak bonds, coordination defects at general boundaries or defects in coincidence tilt boundaries were the source of band tails or deep states.

M.Kohyama: Materials Science Forum, 1996, 207-209, 265-8