On Thu, Mar 1, 2012 at 11:36 PM, Vellieux Frederic
And I'd certainly start refinement using the NCS present, to relax it (restraints) as the refinement proceeds (smoothly) and possibly not use any NCS in the final stages of the refinement. You may need to carry out annealing initially and so forth.
Fred is correct, you absolutely want to use NCS at this resolution - if you use the torsion NCS parameterization (get a new-ish build for this), you probably will not need or want to turn off the restraints. The other thing to try is optimizing the X-ray/stereochemistry weight. This can take quite a long time (unless you have a large multi-core system), but it almost always yields a better result. You might also want to turn off the real-space refinement, sometimes it behaves weirdly. At 2.4A with an R-free of 0.32 you can probably start running the ordered solvent update, which will help a little bit. A more general suggestion is to look through the log file and identify where the R-factors begin to explode. This will give you a better idea where you need to change your strategy. Final suggestion: make sure you're running at least version 1.7.3, since there have been many improvements to refinement of more marginal cases. -Nat