Dear all, I'm refining a 1.45 Ang structure in which I have several residues that have alternate conformations. These alternate conformations in some cases coincide with additional density that suggests the presence of a water molecule, appropriately positioned to make hydrogen bonds with near atoms. I have modeled partially occupied waters in these additional densities and linked their occupancies with the alternate conformation that is not clashing with the water in question. My problem is that these partially occupied waters are pushed away by the 'overlapping' alternate conformation of the amino acids. I guess there's an antibump restraint somewhere? How can I tell phenix that these alternate waters are not sterically clashing with the amino acid (since the sum occupancies of the water plus alternate conformation is 1)? The attached image shows one of those disordered residues after refinement. Water 1519 is pushed away from one alt conf (A) of Gln13, whereas the density suggests it should be making a hydrogen bond to OE1 of the altconf B of Gln13. I describe the occupancies of the situation in the attached image as below. refinement { refine { occupancies { constrained_group { selection = chain A and resseq 13 and altloc A selection = (chain A and resseq 13 and altloc B) or (resname HOH and resseq 1519 and altloc A) } } } } Thanks, Roeland Boer.
