[phenixbb] detwin data

Peter Zwart PHZwart at lbl.gov
Wed Oct 8 14:13:09 PDT 2008


For what do you need detwinned data? What is your twin fraction / law?
When twin fraction is above 45%, algebraic detwinning will give weird results.

Phase info with twinned refinement is not possible with phenix.refine.


2008/10/8 Ralf W. Grosse-Kunstleve <rwgk at cci.lbl.gov>:
>> I've used the phenix.refine with its detwin function.  Is there any way to
>> have a detwinned data output so that I can use it for other things.
>> I tried use CCP4 detwin with the same twin law and twin fraction obtained
>> from Phenix.  However, this didn't work.
> I hope Peter will comment on this.
>> Another question is whether I can use "some" phase information, say from DM
>> into Phenix?  I tried to include the PHIDM but Phenix complained about it
>> saying "wrong array".
> phenix.refine needs Hendrickson-Lattman coefficients. Often they are
> called HA,HB,HC,HD. I'm not sure if DM produces Hendrickson-Lattman
> coefficients, but it seems highly likely. You should be able to
> simply give the DM file with the Hendrickson-Lattman coefficients to
> phenix.refine; it should pick the arrays automatically. If your Fobs
> and R-free flags are also in the DM file (in addition to the original
> data file), phenix.refine may prompt you to specify which copy
> you want. Then add one of the phenix.refine suggestions to the
> phenix.refine command line.
> Ralf
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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
BCSB:     http://bcsb.als.lbl.gov
PHENIX: http://www.phenix-online.org
CCTBX:  http://cctbx.sf.net

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