Hello, I have many Osmium ions in my structure. They have 6 coordinated ammonium groups and I would like to refine the B-factors for them: one B-factor for Os in each residue and one B-factor for all 6 ammonium groups in each residue. For this I have chosen *group_adp with following syntax adp { group_adp_refinement_mode = one_adp_group_per_residue \ two_adp_groups_per_residue *group_selection group = chain O and element Os group = chain O and element N } I wanted to refine only B-factor for Osmiums in this refinement. To avoid the bias from previously refined values of B-factor I presetted B-factors for all Osmiums to 50. As a result I got the change of B-factors for all residues in the model to the same value (which probably means that all model was refined as one group) and R-free increased from 0.25 to 0.34. What should be the correct syntax for this refinement? Should I also refine ions coordinates for a good refinement of B-factors? Irina