Difference between revisions of "Laue class"
From Online Dictionary of Crystallography
AndreAuthier (talk | contribs) |
|||
| Line 1: | Line 1: | ||
| − | <Font color="blue"> Classes de Laue </Font> (''Fr''). <Font color="red"> Laue Klassen</Font> (''Ge'').<Font color="green"> Clases de Laue </Font> (''Sp''). | + | <Font color="blue"> Classes de Laue </Font> (''Fr''). <Font color="red"> Laue Klassen</Font> (''Ge'').<Font color="green"> Clases de Laue </Font> (''Sp'').<Font color="black"> Classi di Laue </Font>(''It'') |
| + | |||
== Definition == | == Definition == | ||
Revision as of 14:24, 28 March 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 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