Hello, it would be helpful to see screenshots of a couple of diffraction images from each crystal. The refinement, etc, in mosflm et al can be thrown off a bit, I think, if you are too optimistic about the outer resolution limit. Do the spots look split and are you confident about the beam centre? If you are only predicting 25% of the spots it sounds, as you implied, like a cell and symmetry problem.
Best wishes, Jon Cooper. jon.b.coo...@protonmail.com -------- Original Message -------- On 2 Oct 2020, 16:04, Xu, Shenyuan wrote: > Dear CCP4 community, > > I have two challenging datasets for indexing, one has very strong > diffraction, the other one has very weak spots. I know both crystals are not > very good, knocked down from a big chunk of crystal. > > For the dataset 1, first I use iMosflm to index it, but it can not refine it > as "Detector tilt and twist parameters vary substantially". Based on the > penalty value and RMSD, the index solution is not satisfactory. Then I moved > to Xia2 from CCP4i, no index solution was found. Then I use Dials, it can > successfully index the data, but only about 25% spots have been indexed, and > the rmsd is not very good. I forced it to proceed, and after integration, the > statistics seem to be good, but I can not use MR to solve the structure (If > the index is good, I think MR can solve it as I did it before). I have gone > through all the troubleshooting suggestions that are available online for > iMosflm and Dials, but no improvement. > > For the dataset 2, I think the main reason is because of the weak > diffraction. Both iMosflm and Dials can not give good results. > > The best way may be to optimize the crystal. But I feel like there may be a > better way to optimize the parameters to index it. The datasets are large, I > can send you privately by email if you are interested to take a look. > > I really appreciate your suggestions. > > Thanks, > Shen > > --------------------------------------------------------------- > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
