Dear All, 1. I would like to do occupancy refinement for several sulfat (and HEPES; 3-letter code EPE) molecules (nothing specific in mailing list and documentation about this). If I set the occupany in coot to a value between 0 and 1 it works perfect. However I want to do this in the future giving a occ.params file or with the gui. a) In gui under refinement settings --> mody selection for -->ocupancies--> individual selection I put SO4 I get an error saying AtomSelectionError b) adding an occ.params file to the input files refinement { } refine { occupancies { individual = resname SO4 remove_selection = None constrained_group { selection = None } } } leads to phenix error RuntimeError: atom selection syntax error at word "so4". Atom selection string leading to error: SO4 What am I doing wrong? Thank you very much in advance, best regards Georg.