Hi Young-Jin,

I am just wondering while I was taking a small molecule X-ray course. I used to run refinement with anisotropic ADP when it is high resolution about better than 1.5 or 1.6 A. My question is when you do this with occupancy refinement, does phenix.refine take care the alternative conformations with aniostropic ADP (I guess so) even at low occupancy?

occupancy refinement in phenix.refine: http://phenix-online.org/documentation/refinement.htm#anch20

Due to lack of electrons (scattering factor), I experienced that small molecule refinement applies Anisotropic ADP for the atoms (about more than 2 e- in occupancy) while applying isotropic ADP for the less occupied atoms (in an alternative conformation). Would it help if we apply this method to our macro molecular system when you have residues that have low occupied alternative residues? Is so, could we have something like script or else either to modify a pdb file or to make this in consideration during refinement?

I'm sure I see the rationale here: why partially occupied atoms should be assumed moving isotropically while fully occupied atoms should be refined with anisotropic ADPs ? Am I missing something? Pavel.