Yes, I would agree with Francis that diffraction shows contribution from several lattices, which could lead to misindexing. However, it should be feasible to get a model that refines from this sort of data.
Pramod - could you please post your data processing statistics from your scaling program? Better if you have several for different spacegroups. Also, I have no idea how HKL200 does this, but could you please provide an indexing solution table from Mosflm that shows penalties associated with each type of space group? Was there a sharp penalty drop at some point or was it more gradual? When you index spots in Mosflm, do your predictions agree with the spots? Or is there a substantial portion that are missed? I would consider altering thresholds in Mosflm for indexing (see the manual). Eugene On 19 June 2013 17:34, Francis E. Reyes <francis.re...@colorado.edu> wrote: > On Jun 17, 2013, at 12:36 PM, Pramod Kumar <pramod...@gmail.com> wrote: > > >> I have a crystal data diffracted around 2.9 A*, > >> during the data reduction HKL2000 not convincingly showed the space > group (indexed in lower symmetry p1), while the mosflm given C-centered > Orthorhombic, and again with little play around HKL2000 given CO > > > > > > > no ice ring is appeared, diffraction pattern looks ok, misindexing in > any direction is not conclusive to me (plz see the imj attachment) > > The diffraction does not look ok... there's hints of multiple lattices... > which is not a problem if the two lattice orientations do not perfectly > overlap (i.e. their spots are separable). > > Last I remember, HKL2000 bases its indexing on the 'strongest' spots on an > image (though you could manually select spots). It could result in a > misindex if the strongest spots come from separate lattices (and even worse > if you have twinning/pseudosymmetry issues). > > Try a program that uses all spots for indexing, across all images (XDS for > example) and you might get the true space group. > > Or if the crystal is big enough, you could try shooting it in different > areas and 'searching' for a better spot to collect data. > > Or 'grow a better crystal'. > > F > > > > --------------------------------------------- > Francis E. Reyes PhD > 215 UCB > University of Colorado at Boulder > -- Dr Eugene Valkov MRC Laboratory of Molecular Biology Francis Crick Avenue Cambridge Biomedical Campus Cambridge CB2 0QH, U.K. Email: eval...@mrc-lmb.cam.ac.uk Tel: +44 (0) 1223 407840
