Hi, All Phenix Users, I am fitting 2-bromoethanol to the density map. I want to keep its gauche conformation, so I edited the cif for this ligand to restrain the torsion angle, loop_ _chem_comp_tor.comp_id _chem_comp_tor.id _chem_comp_tor.atom_id_1 _chem_comp_tor.atom_id_2 _chem_comp_tor.atom_id_3 _chem_comp_tor.atom_id_4 _chem_comp_tor.value_angle _chem_comp_tor.value_angle_esd _chem_comp_tor.period BRJ Var_01 BR1 CB CB1 OB1 -60.00 0.0 3 But, after refinement, this angle can be close to 90 or even 120. Even worse is that the fitting at such angles are not better than at -60/60 angle. How could I fix/restrain the angle during refinement? Thanks! Charles *************************************************** Charles Chen Research Associate University of Pittsburgh School of Medicine Department of Anesthesiology ******************************************************