View source for Symmetry and space groups

Space group operators can be found here: http://www.embl-hamburg.de/~pinotsis/spacegroup.html

The crystallographic toolbox is at [http://cci.lbl.gov/cctbx/]. Its predecessor, SgInfo, is [http://cci.lbl.gov/sginfo/ here].


== Facts about space groups ==
There are 230 space groups, 65 of which accessible to proteins.

Empirically, P2<sub>1</sub>2<sub>1</sub>2<sub>1</sub> is the space group which occurs most often (23%) in the [http://www.rcsb.org PDB]; second place is P2<sub>1</sub> with 14.4%, then comes C2 (9.0%) ( [http://www.rcsb.org/pdb/statistics/histogram.do?mdcat=symmetry&mditem=space_group_name_H-M&numOfbars=200]).

== Reflection conditions ==

These are explained and listed in Section 2.2.13 of International Tables of Crystallography, Volume A . If this is not on your desk, check out the [http://reference.iucr.org/dictionary/Main_Page IUCr wiki]:

[[iucr:Reflection_conditions|Reflection_conditions]] which explains the topic, and links to lists of the general absences in article [[iucr:Integral_reflection_conditions|integral reflection conditions]], and the absences along the screw axes in [[iucr:Serial_reflection_conditions|serial reflection conditions]].