<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:'times new roman', 'new york', times, serif;font-size:12pt"><div>Hello,</div><div><br></div><div> I am needing to include a single hydroxide ion in my simulation - is there a force field available in Gromacs that is already parameterized, or do I need to create from scratch? With regards to topology, same question, especially as PRODRG does not do mono or diatomics. Any guidance anyone could provide would be very much appreciated. I have tried searching the archives but didn't find anything.</div><div><br></div><div>Thanks </div><div><br></div><div>Marc Charendoff </div><div style="position:fixed"></div></div></body></html>