# Laue class

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 Revision as of 05:44, 26 March 2006 (view source)← Older edit Revision as of 07:36, 26 March 2006 (view source)Newer edit → Line 6: Line 6: +
+ {| border cellspacing="0" cellpadding="5" align=center> + + |Laue class||Non-centrosymmetric groups having the same Laue class + |- + | ${\bar 1}$|| 1 + |- + |2/''m''|| 2, ''m'' + |- + |''mmm''|| 222, 2''mm'' + |- + |${\bar 3}$|| 3 + |- + |${\bar 3}m$|| 32, 3''m'' + |- + |4/''m''|| 4, ${\bar 4}$ + |- + |4/''mmm''|| 422, ${\bar 4}2m$, 42''m'' + |- + |6/''m''|| 6, ${\bar 6}$ + |- + |6/''mmm''|| 622, ${\bar 6}2m$, 62''m'' + |- + |$m{\bar 3}$|| 23 + |- + |$m{\bar 3}m$|| 432, ${\bar 4}$32 + |} + + +
Laue class Non-centrosymmetric groups
having the same Laue class
${\bar 1}$ 1
2/''m'' 2, ''m''
''mmm'' 222, 2''mm''
${\bar 3}$ 3
${\bar 3}m$ 32, 3''m''
4/''m'' 4, ${\bar 4}$
4/''mmm'' 422, ${\bar 4}2m$, 42''m''
6/''m'' 6, ${\bar 6}$
6/''mmm'' 622, ${\bar 6}2m$, 62''m''
$m{\bar 3}$ 23
$m{\bar 3}m$ 432, ${\bar 4}$32
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + == See also == == See also ==

## Revision as of 07:36, 26 March 2006

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 impossible to distinguish by diffraction between a centrosymmetric point group and one of its non-centrosymmetric subgroups.

 Laue class Non-centrosymmetric groups having the same Laue class ${\bar 1}$ 1 2/m 2, m mmm 222, 2mm ${\bar 3}$ 3 ${\bar 3}m$ 32, 3m 4/m 4, ${\bar 4}$ 4/mmm 422, ${\bar 4}2m$, 42m 6/m 6, ${\bar 6}$ 6/mmm 622, ${\bar 6}2m$, 62m $m{\bar 3}$ 23 $m{\bar 3}m$ 432, ${\bar 4}$32

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Laue class Non-centrosymmetric groups
having the same Laue class
${\bar 1}$ 1
2/m 2, m
mmm 222, 2mm
${\bar 3}$ 3
${\bar 3}m$ 32, 3m
4/m 4, ${\bar 4}$
4/mmm 422, ${\bar 4}2m$, 42m
6/m 6, ${\bar 6}$
6/mmm 622, ${\bar 6}2m$, 62m
$m{\bar 3}$ 23
$m{\bar 3}m$ 432, ${\bar 4}$32