Hi All, I was successfully able to change a few atom types using the setattr command. I checked to see that the atoms I changed were correct (by selecting the atoms and then then clicking the IDATM type option.) I saved the .pdb file When I opened up the saved .pdb file and checked the atom types, they had reverted back to their original type. Is there a specific way to save files after using setattr command? Regards, Juliette Cao University of Houston