International
Tables for
Crystallography
Volume A
Space-group symmetry
Edited by Th. Hahn

International Tables for Crystallography (2006). Vol. A. ch. 1.4, p. 8

Section 1.4.4. Notes on graphical symbols of symmetry planes

Th. Hahna*

aInstitut für Kristallographie, Rheinisch-Westfälische Technische Hochschule, Aachen, Germany
Correspondence e-mail: hahn@xtal.rwth-aachen.de

1.4.4. Notes on graphical symbols of symmetry planes

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  • (i) The graphical symbols and their explanations (columns 2 and 3) are independent of the projection direction and the labelling of the basis vectors. They are, therefore, applicable to any projection diagram of a space group. The printed symbols of glide planes (column 4), however, may change with a change of the basis vectors, as shown by the following example.

    In the rhombohedral space groups [R3c] (161) and [R\bar{3}c] (167), the dotted line refers to a c glide when described with `hexagonal axes' and projected along [001]; for a description with `rhombohedral axes' and projection along [111], the same dotted glide plane would be called n. The dash-dotted n glide in the hexagonal description becomes an a, b or c glide in the rhombohedral description; cf. the first footnote[link] in Section 1.3.1.

  • (ii) The graphical symbols for glide planes in column 2 are not only used for the glide planes defined in Chapter 1.3[link] , but also for the further glide planes g which are mentioned in Section 1.3.2[link] (Note x[link] ) and listed in Table 4.3.2.1[link] ; they are explained in Sections 2.2.9[link] and 11.1.2[link] .

  • (iii) In monoclinic space groups, the `parallel' glide vector of a glide plane may be along a lattice translation vector which is inclined to the projection plane.

  • (iv) In 1992, the International Union of Crystallography introduced the `double' glide plane e and the graphical symbol ..--..-- for e glide planes oriented `normal' and `inclined' to the plane of projection (de Wolff et al., 1992[link]); for details of e glide planes see Chapter 1.3[link] . Note that the graphical symbol [\downarrow\hskip -6pt\raise5pt\hbox{$\rightarrow$}] for e glide planes oriented `parallel' to the projection plane has already been used in IT (1935)[link] and IT (1952)[link].

References

First citationInternationale Tabellen zur Bestimmung von Kristallstrukturen (1935). I. Band, edited by C. Hermann. Berlin: Borntraeger. [Reprint with corrections: Ann Arbor: Edwards (1944). Abbreviated as IT (1935).]Google Scholar
First citationInternational Tables for X-ray Crystallography (1952). Vol. I, edited by N. F. M. Henry & K. Lonsdale. Birmingham: Kynoch Press. [Abbreviated as IT (1952).]Google Scholar
First citationWolff, P. M. de, Billiet, Y., Donnay, J. D. H., Fischer, W., Galiulin, R. B., Glazer, A. M., Hahn, Th., Senechal, M., Shoemaker, D. P., Wondratschek, H., Wilson, A. J. C. & Abrahams, S. C. (1992). Symbols for symmetry elements and symmetry operations. Final Report of the International Union of Crystallography Ad-hoc Committee on the Nomenclature of Symmetry. Acta Cryst. A48, 727–732.Google Scholar








































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