Thanks, Peter! Your help was invaluable as always.

Thanks, Peter. I had been confusing the CharmmPsfFile with a Forcefield. What I'm trying to do, in a nut shell, is read a protein structure, add water, and simulate using the CHARMM 22 forcefield. OpenMM supports building a system and simulation from CHARMM files -- but I don't see a provided CHARMM...

Hi Peter, Thanks for the quick response! Using pdb.topology, I get the following error: File "prepare-water-box.py", line 31, in create_system modeller.addSolvent(psf, boxSize=[5.0, 5.0, 5.0]) File "/usr/lib64/python2.7/site-packages/simtk/openmm/app/modeller.py", line 317, in addSolvent system = fo...

Hi, I'm trying to use the Modeller class to add explicit waters to a protein. I have PDB and PSF files for the protein and topology and parameter files for CHARMM. The addSolvent() method seems inconsistent as to what topology and forcefield should be but I could just be confused. psf = CharmmPsfFil...