Bloch wave notation in many-beam electron diffraction theory

There are a number of different Bloch wave labelling systems currently in use in the theory of the diffraction of electrons by crystals. It is suggested that the Bloch wave labelling scheme for electron diffraction which is the simplest and the most logical is an ordered labelling scheme in which the top branch of the dispersion surface corresponds to wave 1, the second branch to wave 2, the third branch to wave 3, and so on. Such a scheme would be consistent with accepted notations in other forms of Bloch wave propagation. The essential mathematical unity of all forms of wave propagation in crystals is discussed, and the use of the proposed notation in describing the critical voltage effect is briefly considered.