Additional symmetry elements

Bertaut, E. F.

doi:10.1107/97809553602060000509

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

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International Tables for Crystallography (2006). Vol. A. ch. 4.3, p. 71

Section 4.3.4.3. Additional symmetry elements

E. F. Bertaut^a ^‡

^a Laboratoire de Cristallographie, CNRS, Grenoble, France

4.3.4.3. Additional symmetry elements

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As a result of periodicity, in all space groups of classes 422, $[\bar{4}m2]$ and $[4/m\; 2/m\; 2/m]$ , the two tertiary diagonal axes 2, along [ $[1\bar{1}0]$ ] and [110], alternate with axes $[2_{1}]$ , the screw component being $[{1 \over 2},\mp]$ $[{1 \over 2}]$ , 0 (cf. Table 4.1.2.2 ).

Likewise, tertiary diagonal mirrors m in x, x, z and $[x,\bar{x},z]$ in space groups of classes 4mm, $[\bar{4}2m]$ and $[4/m\; 2/m\; 2/m]$ alternate with glide planes called g,¹ the glide components being $[{1 \over 2}]$ , $[\pm {1 \over 2}]$ , 0. The same glide components produce also an alternation of diagonal glide planes c and n (cf. Table 4.1.2.2 ).

References

International Tables for Crystallography (2006). Vol. A. ch. 4.3, p. 71