Difficult datasets
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Small-molecule and low resolution protein datasets have few reflections per frame. Therefore, the multitude of parameters describing the diffraction experiment probably needs to be reduced. This means that e.g. the following parameters may need adjustment (typical values are given):
- NBATCH=2 ! to reduce the number of scale factors
- DELPHI=45 ! to base reflection profiles and refinements on more reflections
- REFINE(INTEGRATE)= ! do not refine anything
- CORRECTIONS= ABSORB ! don't try to correct for MODULATION and DECAY in scaling
Furthermore, you may try to recycle GXPARM.XDS to XPARM.XDS, and to grab the lines e.g.
BEAM_DIVERGENCE= 2.067 BEAM_DIVERGENCE_E.S.D.= 0.207 REFLECTING_RANGE= 2.303 REFLECTING_RANGE_E.S.D.= 0.329
from INTEGRATE.LP and to insert them into XDS.INP .