The potential energy curves for Fe-acceptor pairing reactions were investigated by using an  ab initio  molecular orbital method which involved cluster models. The calculated potential energy curves correctly reproduced the relative stability of trigonal and orthorhombic configurations. An analysis of the electronic distributions revealed that the Fe was directly bound to Si atoms next to an acceptor. It was suggested that the activation of these Si atoms was at the origin of the attractive interaction in pairing reactions.

M.Sugimoto, A.Seki: Materials Science Forum, 1995, 196-201, 1339-44