Hello, We need to run MD simulations to measure the dynamics of localized waters in PDB structures. The localized waters are designated HOH, rather than recognized model types such as TIP3P etc. Can one replace "HOH" in the PDB file with "TIP3P" (for example) so that the localized water positions will be recognized by NAMD and other MD simulation software? Alternatively, are there parameters and topology files that recognize the "HOH" designation? Shahid -- Dr. Shahid Khan Senior Scientist Molecular Biology Consortium Lawrence Berkeley National Laboratory