Centric and acentric reflections: Difference between revisions

m
Line 22: Line 22:


To find centric reflections, we just solve the Eigenvalue problem A v = v, now considering each reciprocal space symmetry operator in turn.
To find centric reflections, we just solve the Eigenvalue problem A v = v, now considering each reciprocal space symmetry operator in turn.
Centric reflections in space group P2 and P2_1 are thus those with 0,k,0.
Centric reflections in space group P2 and P2<sub>1</sub> are thus those with 0,k,0. There exist space groups without centric reflections, like R3.


Properties: centric reflections have only two phase possibilities, e.g. 0° and 180° (but in any case 180° apart), and centric reflections do not have an anomalous signal (can these properties be easily derived here?). Furthermore, the "intensity statistics" of centric reflections  
Properties: centric reflections have only two phase possibilities, e.g. 0° and 180° (but in any case 180° apart), and centric reflections do not have an anomalous signal (can these properties be easily derived here?). Furthermore, the "intensity statistics" of centric reflections  
Line 29: Line 29:


Centric reflections have a special role in experimental [[phasing]].
Centric reflections have a special role in experimental [[phasing]].
There exist space groups without centric reflections, like R3.


== References ==
== References ==
1,330

edits