[Chimera-users] Minimize hydrogens in water molecules

Hi, I need to minimize two water molecules in the binding site of the protein: I don't want to move the oxygen, so I've selected only hydrogen atoms and then I' ve used the Minimize Structure tool (keeping fixed all atoms that are unselected). I can't do the minimization because there's an error: Chimera/MMTK cannot minimize structure, probably because there is no parameter for ''No parameters for bond Atom 0.CYS_394__0_0_1_397__A.N (atom type n) - Atom 0.GLY_393__0_0_1_396__A.peptide.C (atom type C)'' I don't known what this means and what I should do to fix it. I've tried to use the command line, but there's another error. Does anyone have suggestions? Thank you. Francesca