Trigonal space groups have a choice of two arbitrary "settings."
Were all those 180 frames collected in one pass? What were the
integration statistics?
What was the phasing method? Did you have a pre-existing structure*,
molecular replacement, anomalous, or what?
* This is the one I am concerned about. If you had a pre-existing
structure in this same crystal form, but then used some newly collected
data, it may not be in the same setting as the original.
On 01/23/12 16:48, Sam Arnosti wrote:
> Hi every one
>
> I have some crystals in the space group P3121. I collect 180 frames of data.
>
> My crystals do not diffract better than at most 2.0 angstrom, but the Rf barely goes below 23%,
>
> and Rfree also remains somewhere between 28-33%. I have tried to refine my data as much as I can.
>
> I do not know whether the problem is because of the bad diffraction or collecting extra frames.
>
> The structure factors are also high but they get better as the crystals diffract better.
>
> Thanks
>
> Sam
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All Things Serve the Beam
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David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
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