[phenixbb] Twin Law question

Young-Jin Cho yjcho at brandeis.edu
Wed Oct 27 13:33:21 PDT 2010

Dear Phenix users,
Thanks in advance to answer my question.

As my recent data did not give me perfect statistics, I was wondering what the problem was (one of things is ice ring though).  When I ran Xtriage with my struggling current data set and looked like I got twinned data.  I reran PHASER as was suggested and confirmed that current space group is right.  My question is now how I can handle this problem.  First, as was recommended I input twin_law, however not all the cases (I have a couple of data sets) were working. One favorite(!) error message was as following:

"Map type 'Fc' not supported for twinned structures. Allowed types: Fo-Fc, Fobs-Fobs-Fmodel, 2mFo-DFc, 2mFobs-DFmodel, mFo-DFc, mFobs-DFmodel, gradient, m_gradient."
I got this from both GUI and shell environment.


1. Now from now on, whenever I want to phenix.refine, should I include twin_law command such as 'twin_law=-h,l,k'?

2. In this case, what do I expect to see such as lowering Rfree or else? If it doesn't help lowering Rfree, what to do next?

3. Do I have to report I did with twinlaw option in case of preparing a paper or presentation? I mean I also heard that if one got twinned data, they re-collected data. How much can I convince my refinement is OK with twined data?

Additionally, I checked other data, and applied twin_law but the result R/Rfree were exactly same as the one I refined without twin_law option, it this normal case?

With many thanks in advance,

Young-Jin Cho

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