Dear All user There are 350 decane molecules in my simulation box, I like doing a simulation(npt ensemble) by a united atom force field, Can I use the opls (nonbonded: L-J 6-12 and coloumb) that is in gromacs? Beside, How can I neglect coloumb interaction(non-bonded) and dihedrals(bonded)? -- Sincerely Ali Alizadeh