Yes, the 1 in these space group names is the same as the 1 in P1. 1 is the identity symmetry operator.
For a trigonal space group (and hexagonal) the symmetry operators are given in an axis order of (z) (a,b) and (i) where i is defined by the ab vector (the ab diagonal) So, for example in space group 149, P312 The z axis has 3-fold symmetry The a and b axes have identity symmetry The i axis (ab diagonal) has 2-fold symmetry HTH, Chris -- Christopher L. Colbert, Ph.D. Assistant Professor Department of Chemistry and Biochemistry North Dakota State University From: Mark van Raaij <[email protected]<mailto:[email protected]>> Reply-To: Mark van Raaij <[email protected]<mailto:[email protected]>> Date: Wednesday, February 18, 2015 4:10 AM To: CCP4 bulletin board <[email protected]<mailto:[email protected]>> Subject: Re: [ccp4bb] P3212--1's in Space Group Names? the same as the 1 in P1 ;-) seriously, if you look at space group names: 143 P3 144 P31 145 P32 149 P312 151 P3112 153 P3212 150 P321 152 P3121 154 P3221 the 1s in 149 to 154 are necessary to differentiate them all. On 18 Feb 2015, at 04:51, Keller, Jacob wrote: Dear Crystallographers, I don't understand what the 1's are doing in space group names like P3212 or P3112--can someone fill me in? Not easy to google this one. JPK ******************************************* Jacob Pearson Keller, PhD Looger Lab/HHMI Janelia Research Campus 19700 Helix Dr, Ashburn, VA 20147 email: [email protected]<mailto:[email protected]> ******************************************* Mark J van Raaij Lab 20B Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC c/Darwin 3 E-28049 Madrid, Spain tel. (+34) 91 585 4616 http://www.cnb.csic.es/~mjvanraaij
