[gmx-users] about total charge

[Rui Li]

Dear all,

When I use grompp,it warns:
NOTE:
  System has non-zero total charge: 1.172000e+01

So I add 12 Cl- in my system.
Then I use grompp again,it warns:  
NOTE:
  System has non-zero total charge: -2.799983e-01

How can I make the total charge zero?