An explanation was presented for the appearance of O-points which were observed in addition to those predicted by Bollmann’s equation. This involved the use of a more general 3-dimensional method for calculating the O-lattices of rotation-related interfaces. A geometrical interpretation of the physical significance of extra O-points was given in terms of atomic matching of adjacent crystal planes in the boundary region. An expression was also derived for the pseudo-inverse of Frank’s formula.

Analysis of Extra O-Points Found in Low Angle 110 Twist Boundaries - a General Solution for O-Lattices in Three Dimensions. D.Romeu, A.Gómez: Scripta Materialia, 2001, 44[11], 2617-22