# Laue class

(Difference between revisions)
 Revision as of 07:36, 26 March 2006 (view source)← Older edit Revision as of 07:45, 26 March 2006 (view source)Newer edit → Line 3: Line 3: == Definition == == 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. + 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. Line 9: Line 9: {| border cellspacing="0" cellpadding="5" align=center> {| border cellspacing="0" cellpadding="5" align=center> - |Laue class||Non-centrosymmetric groups having the same Laue class + |Laue classes||Non-centrosymmetric groups
having the same Laue class |- |- | ${\bar 1}$|| 1 | ${\bar 1}$|| 1 Line 33: Line 33: |$m{\bar 3}m$|| 432, ${\bar 4}$32 |$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
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## Revision as of 07:45, 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 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 ${\bar 1}$ 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