Dear Phenix developers, I'd like to refine (using phenix.refine) a _very_ incomplete model (obtained by molecular replacement with one subunit of the complete structure) against the native amplitudes, with the goal to obtain meaningful phases and figures_of_merit which should serve to find heavy atom sites in derivative datasets. If I "just refine" in phenix.refine, then the R-factors are in the 50s and the program estimates the coordinate error to be very large. Thus I would like to tell phenix.refine that the coordinates are actually quite accurate, but that a lot of the model is simply missing. I found alpha_beta free_reflections_per_bin= 140 number_of_macromolecule_atoms_absent= 225 n_atoms_included= 0 bf_atoms_absent= 15.0 final_error= 0.0 absent_atom_type= "O" method= *est calc estimation_algorithm= *analytical iterative verbose= -1 interpolation= True fix_scale_for_calc_option= None number_of_waters_absent= 613 sigmaa_estimator kernel_width_free_reflections= 100 kernel_on_chebyshev_nodes= True number_of_sampling_points= 20 number_of_chebyshev_terms= 10 use_sampling_sum_weights= True in the documentation but I have trouble understanding its meanings and defaults - but I do think this should be used. Maybe I should switch to method=calc and specify number_of_macromolecule_atoms_absent= as well as bf_atoms_absent= ? Can anyone advise me, please? thank you, Kay