Laue class
From Online Dictionary of Crystallography
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Revision as of 07:45, 26 March 2006 by AndreAuthier (talk | contribs)
Classes de Laue (Fr). Laue Klassen (Ge). Clases de Laue (Sp).
Definition
The Laue classes correspond to the eleven centrosymmetric point groups. When absorption is negligible and Friedel's law applies, it is impossible to distinguish by diffraction between a centrosymmetric point group and one of its non-centrosymmetric subgroups.
Laue classes | Non-centrosymmetric groups having the same Laue class |
[math]{\bar 1}[/math] | 1 |
2/m | 2, m |
mmm | 222, 2mm |
[math]{\bar 3}[/math] | 3 |
[math]{\bar 3}m[/math] | 32, 3m |
4/m | 4, [math]{\bar 4}[/math] |
4/mmm | 422, [math]{\bar 4}2m[/math], 42m |
6/m | 6, [math]{\bar 6}[/math] |
6/mmm | 622, [math]{\bar 6}2m[/math], 62m |
[math]m{\bar 3}[/math] | 23 |
[math]m{\bar 3}m[/math] | 432, [math]{\bar 4}[/math]32 |
See also
Section 3.1 of International Tables of Crystallography, Section A