International
Tables for Crystallography Volume C Mathematical, physical and chemical tables Edited by E. Prince © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. C. ch. 9.8, p. 912
Section 9.8.1.4.4. Generalized nomenclature |
In Section 9.8.4, the theory is extended to structures containing d modulations, with . In this case, each point-group transformation in internal space is given by and the associated internal translation by the (d-dimensional) vector . Thus, The transformations R and are represented by the matrices and , respectively. In the following discussion, this nomenclature (but with vI rather than vI) is sometimes also applied for the (3 + 1)-dimensional case. The usual formulae are obtained by replacing RI by ɛ and vI by Δ.