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Difference between revisions of "Laue class"

From Online Dictionary of Crystallography

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== Definition ==
 
== 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.
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The Laue classes correspond to the eleven centrosymmetric crystallographic 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.
  
  

Revision as of 15:41, 8 May 2006

Classes de Laue (Fr). Laue Klassen (Ge). Clases de Laue (Sp). Classi di Laue (It)


Definition

The Laue classes correspond to the eleven centrosymmetric crystallographic 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