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If you read the .sca file into XPREP it will ignore the space group name in the file and determine the possible space group(s) from the data. If this requires reindexing it will do that too, and optionally it will also merge equivalents in the new space group. It would be better to read in unmerged data, but it will still work fine with data that have been averaged in P3. Of course it cannot distinguish between P3121 and P3221, you have to solve the structure to resolve that. You should keep in mind that merohedral twinning is quite common for trigonal crystals.
George ckielkop wrote:
*** For details on how to be removed from this list visit the *** *** CCP4 home page http://www.ccp4.ac.uk *** Apologies for these slightly off-topic questions about changing space groups, particularly in Scalepack- 1) We have a '.sca' file processed in p3, and would like to change the space group to p3121 or p3221. We don't have the '.x' files. Is it acceptable to just read in the .sca file and change the symmetry in scalepack? If so, since these are isomorphous, higher symmetry space groups, is no reindexing matrix needed? 2) Can a dataset processed in p3121 be used in P3221 without reindexing? I think the answers to these questions are 'yes', but wanted to double check with the experts. Thank you very much for your help, Clara
-- Prof. George M. Sheldrick FRS Dept. Structural Chemistry, University of Goettingen, Tammannstr. 4, D37077 Goettingen, Germany Tel. +49-551-39-3021 or -3068 Fax. +49-551-39-2582
