[gmx-users] counter ion and charged polymer in gas-phase

[Sanku M]

Hi,
  I am doing simulation of charged polymer . When I do the simulation in water or solvent, I put counter ion in the solvent to neutralize the charge in the system. But, if I want to do the simulation in gas-phase ( i.e no solvent), does adding counter-ion make any sense or is it realistic? I mean : does counterion remain present in gas-phase ?  Or, should I use charged system which might get neutralized by back-ground neutralizing effect of Particle-Mesh Ewald?
Thanks
Sanku