Hi,
Please note that there are 3 different spacegroups directly below
C222(1), namely
C 1 2 1 41.85 181.82 119.48 90.00 90.00 90.00
C 1 2 1 181.82 41.85 119.48 90.00 90.00 90.00
P 1 21 1 41.85 119.48 93.26 90.00 102.89 90.00
[ as obtained by phenix.explore_metric_symmetry --unit_cell="41.8500
119.4800 93.2600 90.0000 102.8880 90.0000" --space_group=P21
--start_from_p1 ]
Note that the two choices of C2 are not equivalent; it looks like you
have missed a space group.
You can try to solve the structure in P1 and from an RvsR analyses
guess which choice is best. Contact me personally on help with that if
so desired.
Cheers
Peter
2008/11/7, Yuan, Hua <[log in to unmask]>:
> Dear All,
>
> I'm trying to decide the spacegroup between P21 and C2 and in need of
> your help.
> I have a data with the following possible cells:
> P21: 41.8500 119.4800 93.2600 90.0000 102.8880 90.0000
> C2: 181.8000 41.8400 119.5300 90.0000 90.0820 90.0000
>
> The data is twinned (C2221 is always suggested by different programs
> without considering twinning). Therefore twin refinement is carried on in
> Phenix.refine, with twin law "h,-k,-h-l" for P21 and "h,-k,-l" for
> C2. Both space groups give a reasonable but not so different R-free
> close to 23% for a 2.3 angstrom data, and the resulted map is also OK
> in both cases. As it is with higher symmetry, maybe I should go with
> C2. But there could be something I missed here, i.e. a pseudosymmetry
> operator taken as crystallographic symmetry? Any suggestions or
> comments are highly appreciated!
>
> Thanks,
>
> Hua
>
--
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P.H. Zwart
Beamline Scientist
Berkeley Center for Structural Biology
Lawrence Berkeley National Laboratories
1 Cyclotron Road, Berkeley, CA-94703, USA
Cell: 510 289 9246
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PHENIX: http://www.phenix-online.org
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