Hi Alex, did you generate free-R flags using phenix.refine? If not, then try this: - create free-R flags from scratch using phenix.refine; - run ~10 refinement macro-cycles with the new flags. If the R-factors are similar, then this is what it is. How the maps look like? Have a look at page #123 here: http://cci.lbl.gov/~afonine/tmp2/PavelAfonine_PHENIX.pdf Let me know if you have questions. Pavel. On 2/16/11 11:52 AM, [email protected] wrote:

Hi -- I have a twinned data set -- approximate twinning fraction of 0.4. I decided to try to try twinned refinement using phenix.refine in what would seem to be the appropriate manner -- from the "All Parameters" menu, I select twinning, hit "Run Xtriage now" on my mtz file, it gives me the input to the "Twin Law", I keep the rest of the values the same (gave no Anisotropy correction), hit OK, then run 3 cycles of refinement. The only thing is that the Rwork/Rfree values are really very good, almost too good to be true -- for my 1.7 A refinement, I have values of 12.4 and 14.8%, respectively for Rwork and Rfree. Is there anything that I may be doing wrong yielding R values which are artifically too low?

Thanks for your help

Alex