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DPS Frequently Asked Questions

If your question about DPS is not answered here please contact Marian Szebenyi, or you can join the DPS mailing list and post queries there.

General

• Why can't I refine orientation and cell parameters for images from a crystal with high mosaicity?
  Mosflm "post-refinement" only works on reflections which extend across exactly two images. If mosaicity is high relative to oscillation width, there may be too few such reflections for refinement to proceed. See next question.

• How can I process my data when mosflm refinement fails?
  First, get the best indexing possible by careful selection of picked spots, resolution limits, and longest cell parameter. Until dps_prerefine is ready, use mosflm indexing (new style), which does a little refinement of camera constants. Use mosflm display to check how many frames are well predicted, and integrate those frames with post-refinemnt turned off (in the Integration Parameters window). Then index on the first frame of those remaining, if any, integrate another batch, and so on. Scale data from all the integration runs together.

Installation

• What do I need to install DPS on my system?
  You need C and Fortran compilers and an X-windows server. You need the CCP4 libraries libccp4f.a, libccp4c.a, and libxdl_view.a, so install CCP4 before DPS.

Display of images

• Why can't I display an image?
  First, check that you have correctly specified the image directory, prefix, run number (if any), current number, and filename template (template in the Detector Parameters window, others on the main window), so that the system can generate the name of the image file you wish to display. If these are correct but the display program is crashing, and you are using precompiled executables, try compiling from source. Programs such as dps_display, which have a lot of X-server calls, are particularly prone to difficulties when compiled under one OS version and run under another.