Hi I would like to know how I can add H atoms to my ligand, ADP in the protein complex. I was trying to add H atoms to one of my ligand, ADP. When I types "phenix.elbow --final-geometry=test10bcoot_h_refine_001.pdb --residue=ADP --output=model_h", it went on but failed with the following error message: Traceback (most recent call last): File "/home2/yjcho/phenix-1.3-final/elbow/elbow/command_line/builder.py", line 1201, in <module> run() File "/home2/yjcho/phenix-1.3-final/elbow/elbow/command_line/builder.py", line 1108, in run molecule = post_process(molecule, options) File "/home2/yjcho/phenix-1.3-final/elbow/elbow/command_line/builder.py", line 577, in post_process options, File "/home2/yjcho/phenix-1.3-final/elbow/elbow/utilities/optimisation_manager.py", line 331, in optimisation_manager pre_opt)) File "/home2/yjcho/phenix-1.3-final/elbow/elbow/chemistry/IOMixins.py", line 857, in WritePDB original_order=original_order, File "/home2/yjcho/phenix-1.3-final/elbow/elbow/chemistry/IOMixins.py", line 965, in WritePDB2String self.AdjustHydrogenNames() File "/home2/yjcho/phenix-1.3-final/elbow/elbow/chemistry/IOMixins.py", line 940, in AdjustHydrogenNames if test_name[3]==" ": test_name[3]="0" TypeError: 'str' object does not support item assignment FYI. ADP is names as ADP as a residue name in the pdb file but has different chain names. By the way, I should mention that I used phenix.reduce first for adding H atoms but it was not able to add sugar H's in ADP molecule albeit other residues were fine. Thanks in advance for your help. Best, YoungJin