Just for the record, if you feed the data into XPREP (using Tim Gruene's mtz2sca if necessary) it will almost certainly give you the choice of space groups - with an indication of which is the most likely - and do the necessary cell and index transformations automatically. I recommend inputting unmerged data in such cases!
George 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 On Fri, 7 Mar 2008, Pietro Roversi wrote: > Dear all, > after much sweat and grief I managed to index my data in > P321 but looking at the symmetry I think they might be C2: reindexing > from P321 to C2 with the 2h+k, k, l operator in sortmtz produces the > right cell (and yes I did tick the "Reduce reflexions to the asymmetric > unit" button so that noreduce is not among the sortmtz keywords): > > P321 209.3168 209.3168 40.6822 90.0000 90.0000 120.0000 > C2 362.5473 209.3168 40.6822 90.0000 90.0000 90.0000 > > But: scala then decides that the asymmetric unit is not the right one > and it mysteriously changes cell parameters (which I think points to a > bug in the sortmtz process of reindexing): > > Reciprocal space symmetry: > Space group: "C 1 2 1" Point group: "PG2" Laue group: "2/m" > Reference asymmetric unit: "k>=0 and (l>0 or (l=0 and h>=0))" > (change of basis may be applied) > > and I end up with this C2 cell in the mtz output from scala: > > 285.9320 285.9320 40.6824 90.0000 90.0000 90.0000 > > I have tried OUTPUT ORIGINAL ans some such in scala but to no avail. > > Now please don't all tell me to go back and reindex-reintegrate these > images - although I might have to do it to get the best out of these > data once I am convinced they are monoclinic. > > Rather, I would appreciate suggestions on what program to feed the > multirecord mtz to sort its asymmetric unit in C2 so that scala does not > play tricks on me; or what keyword to feed scala to keep reflexions in > the current asymmetric unit (and use cad or sftools afterwards on the > scaled/merged file) > > Thanks > > Pietro > > > > -- > Pietro Roversi > Sir William Dunn School of Pathology, Oxford University > South Parks Road, Oxford OX1 3ER, England UK > Tel. 0044-1865-275385 >
