[gmx-users] Add gromacs forcefield w/ virtual site

[chris.neale at utoronto.ca]

Dear Marcelo:

This doesn't address your virtual sites question, but I have used a  
simple oxygen model in the past and posted it to the mailing list:
http://lists.gromacs.org/pipermail/gmx-users/2009-March/040239.html

With regards to your actual query:
1) as far as I know, molecular oxygen does not have a net charge ;)
2) If you do want to create such a topology, the information for how  
to do this is all available in the manual. You're more likely to get  
that kind of assistance if it is clear to us that you have tried to do  
it yourself and have run up against a specific problem.

Chris.

-- original message --

I am trying to simulate oxygen using gromacs but there seems to be no
forcefield parameters for this molecule.

So I would like to add a forcefield to gromacs which is a 3 site model:
The two oxygens are lennard jones particles and there's a point charge
at the center of mass.

The reference article is: "New force fields for nitrous oxide and oxygen
and their application to phase equilibria simulations", Niels Hansen et al

I was wondering if there's anyone more proficient with gromacs that
could indicate me how to do this (files to modify, how to represent the
center of mass particle, etc)

Thank you