The short of the long is that phenix.xtriage on a C2 data set shows twinning with 3 twinning operators (-h,-k-l -k-h-l and k,h,-l).  Pushing it through twin_utils, the soution k,h,-l gives an r/rfree of 0.30 and 0.3014 when the twin fraction is 0.352 .

The question is where to go from here? I try to phenix.refine the same model in phenix.xtriage (except the mtz file is from the latest round of refinement of that model) and the R/Rfree on macro cycle =2  is 30 and 34 . Unfortunately, it doesn't seem to finish the refinement, I get a seg fault.  In the def file for the refinement I set twinning = True and twin_law = k,h,-l . 

I tried to subject the same model and the .ref file to an autobuild passing in a .eff file for refinement specifying the twin_law, and again I get a segfault / crash when refining the input model. 

Please advise!