I'm using Gromacs 5.0.2 for a MD simulation with polymer in a saline solution, but the parameters for the polymers are not know, so I'm using OPLS, but this create a incompatibility with the other components in the simulation.
This is because OPLS is originally developed for a geometric mixing rule for sigma in the LJ 12-6. And the ions and other elements where create with arithmetic rules for sigma.
So, how to combine or adapt in a MD simulation when you have these situation?
Or if there is a set of parameters for polymers that use an arithmetic mixing rule easy to insert in the Gromacs program?