[phenixbb] Odd twinning issue (or maybe all twinning issues are odd by default)

Francis E Reyes Francis.Reyes at Colorado.EDU
Thu Sep 11 12:18:11 PDT 2008


I had a structure that seemed perfectly twinned in P41 21 2,  
completely built to the observable density (no peaks in 2Fo-Fc map  
over 2sigma) and refined to 33/35 (R/Rfree). I indexed, scaled, and  
merged the original unmerged data to P41, molecular replaced using the  
above model. Three rounds of rigid body refinement of the MR solution  
with group adp's dropped R/Rfree to 28/30 (while generating new free R  
flags based on the P41 data). The resolution was to 2.5 so I skipped  
the NCS. Now I try to do a second round of refinement with this time  
individual_sites and individual_adps with no change to the input  
model. The final R/Rfree's are now in the 50's?

Am I missing something (fundamental) ?



Francis Reyes M.Sc.
215 UCB
University of Colorado at Boulder

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