Abstract

The formalism developed in the previous paper Kato, Acta Cryst. (1976), A32, 453-457 is applied to real crystals. If the correlation length of the lattice phase factor is sufficiently smaller than the extinction distance, the ensemble averages of the intensity fields, and , satisfy a set of energy-transfer equations. Their form is essentially the same as that used in the conventional theory of secondary extinction. However, the physical meanings of the coupling constants connecting and are different, so that a modification to the theory of secondary extinction is suggested. The conventional model of mosaic blocks is merely a special case and the theoretical framework is free from the model of distorted crystals.