Hi Mike. I would be more careful about "incorrect" space group. Yes, sometimes auto-indexing gives strange results. However, in your case two sets of crystals differ by two factors, diffraction quality and space group. Therefore it seems more likely that you have two crystal forms. Could you please send me log-files from pointless or ctruncate? Then I would be able to say something more definite.
Regards Andrey On 28 May 2012, at 08:46, Mike John wrote: Hi, All, we got many datasets from crystals of our protein. when the crystal has high quality, it will be indexed as F23 (correct space group). While diffracting poorer, it will be indexed as incorrect space group P4132. The crystals are twined. My question is: Given twinning, why the correct space group F23 will be indexed as an incorrect space group P4132 for most of our crystals (most crystals has poorer quality)? Theoretical analysis of twin operator and symmetry operator to connect F23 and P4132 would be highly appreciated. Thanks Mike
