I am refining a very well ordered structure at 1.45 A and find that after doing just about everything including optimization of weights, etc that there are still areas of positive density residing over S atoms of Met, backbone atoms, etc. I have added hydrogens and used them during refinement as well. The maps are of a high quality and Free R factors are quite good, ~ 17%. Is there anything that can be played with more such as values used in the ADP restraints window to try and achieve a difference map with far fewer areas of significant positive density (all greater then or equal to 4 sigma)?

I am not sure exactly what effect the values of distance power, average power, etc will have on refinement. The other option I was thinking of was the scattering table options. I have other structures of this protein that extend to about 1.2.

Thanks!

Joe