Dear all In the CCP4 documentation about alternative origins for spacegroups (http://www.ccp4.ac.uk/dist/html/alternate_origins.html) one can find the following table:
_________________________________________________ P 1 m 1 SG No: 6 (Standard short HM symbol: Pm) Number of alternate origins: 2 This is a polar spacegroup: the origin is not fixed along the C axis Norigin Xo Yo Zo 1 0.0000 0.0000 ?????? 2 0.0000 0.5000 ?????? _________________________________________________ However, I would expect that the choice of the origin for this space group be arbitrary on the mirror plane, i.e.: _________________________________________________ The origin is not fixed in the AC plane Norigin Xo Yo Zo 1 ?????? 0.0000 ?????? 2 ?????? 0.5000 ?????? _________________________________________________ Similarly, I would expect that the tables for space group P1c1 (No 7), C1m1 (No 8) be different from those in the documentation (I have not checked for other space groups ...) Is it correct what I am saying or am I missing something? Thank you --------------------------------------------------------------------------------------- Stefano TRAPANI Centre de Biochimie Structurale (CBS) CNRS UMR 5048; UM 1; UM 2; INSERM UMR 554 29 rue de Navacelles 34090 MONTPELLIER Cedex, France Tel : +33 (0)4 67 41 77 29 Fax : +33 (0)4 67 41 79 13
