H32 indicates the hexagonal obverse setting (as you list) for a R centered trigonal cell, which is 3x larger than the primitive R32 cell indexed a=b=c, al=be=ga <> 90. Standard imho is the H32 setting, for which I will probably get flamed. The relation between H and R cells is depicted here: http://www.ruppweb.org/Garland/gallery/Ch5/pages/Biomolecular_Crystallography_Fig_5-29.htm
This has been discussed and is explained in the ccp4 tutorials and doc afaik, where you can find more detailed info. For proper format in a journal, I would suggest to adhere to the format given in the ITC (International tables for Crystallography), I.e. Bravais Italic, subscripted screw symbols. Note that this is not the format you put it into most programs - their docs help. You can also try my old space croup decoding program to see general positions, operators, matrices and other useful stuff. http://www.ruppweb.org/new_comp/spacegroup_decoder.htm HTH, BR -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Theresa Hsu Sent: Friday, July 27, 2012 12:54 PM To: [email protected] Subject: [ccp4bb] Space group R32 and H32 Dear all I have a confusion on the space group R32 and H32. For a cell parameter of a = b not equal to c, alpha=beta, not equal to gamma, is it considered as R32 or H32? I tried searching the mail list archives but it does not help a beginner crystallographer like me. I also have another basic question. What is the correct way for writing space groups? Is the Bravais lattice in italic and is there space after that? Or it does not matter because both are used in literature? Thank you.
