[gmx-users] Largest charge group radii for Van der Waals; Largest charge group radii for Coulomb

[Tom]

Dear Gromacs Users,

My file has no problem when i grompp with verison of 4.0.7

When i swith to Gromacs  4.5.3 and grompp my file, it gives this reports:
----------------------------------------------------------------
  NOTE 3 [file grompp.mdp]:
  You are using a plain Coulomb cut-off, which might produce artifacts.
  You might want to consider using PME electrostatics.


Largest charge group radii for Van der Waals: 4.986, 4.983 nm
Largest charge group radii for Coulomb:       6.719, 6.712 nm

WARNING 1 [file grompp.mdp]:
  The sum of the two largest charge group radii (13.430987) is larger than
  rlist (1.200000)
-----------------------------------------------------------------------------------

Is there anyone who can help see why different version mak such
problem? How to solve the problem?

Thanks a lot!

Tom