Dear all, After installing cryo_fit in phenix and gromacs_cryofit on my Macbook Pro M1, I now try to test the code using the example data GTPase. The job encounters immediately a problem but the GUI suggests that the job is still running. The log suggest that the first step did not run successfully (below). I presume setting the topology of the protein but I don’t know. Another question is how is it possible to set other parameters for cryo_fit (like ff…) in the GUI or should I run it in command line ? Thank you for your help and suggestions. Philippe. User's computer's operating system: Darwin ############################################################################################### #################### Step 1: Make gro and topology file by regular gromacs #################### ############################################################################################### Current working directory: /Applications/phenix-1.20.1-4487/modules/cryo_fit/tutorial_input_files/CryoFit_1/steps/1_make_gro command: python 1_before_pdb2gmx_prepare_pdb.py GTPase_activation_center_tutorial.pdb 0 0 0 True Current working directory: /Applications/phenix-1.20.1-4487/modules/cryo_fit/tutorial_input_files/CryoFit_1 This pdb file, /Applications/phenix-1.20.1-4487/modules/cryo_fit/tutorial_input_files/GTPase_activation_center_tutorial.pdb , has 6489 atoms Approximately, for this number of atoms, one 3.1 GHz Intel Core i7 took 7 seconds to make a gro file. command: python 2_runme_make_gro.py /Applications/phenix-1.20.1-4487/modules/cryo_fit/ amber03 True True /usr/local/cryo_fit/cryo_fit/bin// Step 1 didn't run successfully User's command was phenix.cryo_fit /Applications/phenix-1.20.1-4487/modules/cryo_fit/tutorial_input_files/.phenix/project_data/run_1.eff phenix.cryo_fit alone without any arguments introduces full options. If a user sees a message like "Fatal error: Atom xx in residue xx xxx was not found in rtp entry xx with xx atoms while sorting atoms." or "Fatal error: Residue xxx not found in residue topology database" Solution if these residue/atoms are important: Fix wrong names of atoms/residues. Running real_space_refine via phenix GUI will show which atoms need to be fixed. If gromacs amber03 force field doesn't have parameters for these residue/atoms, you may need to add appropriate parameters. If you added parameters, please email me ([email protected]), I want to recognize your contribution publicly. Most MD simulation force fields do not support all kinds of rare residue/atoms. cryo_fit2 is under development to address this issue using phenix.eLBOW Solution if these residue/atoms are not important: Remove these "wrong" atoms/residues from user's input pdb file. Run cryo_fit again. Solution if user's input pdb file is big: Probably cryo_fit will change conformation just minimally, I would extract out these "wrong" atoms/residues from user's input pdb file, then add these extracted lines to cryo_fitted file later. Email [email protected] or [email protected] for any feature request/help.