[gmx-users] Number of ions in Anionic lipid system- Charmm-GUI

[Nidhin Thomas]

Dear GROMACS Users,

I have created a lipid bilayer system (300 POPC + 100 POPG) using CHARMM-GUI.
I want to include 0.150 M KCl in the system. When I use the option in charmm-gui, it gives 98K+ ions and -2 Cl ion. But when I calculated the number of ions using the size of simulation box, I am getting 98 ions. 

Can anyone tell me what I should do to get the exact number of ions in the system?

Would it be correct if I first neutralize the system using 100 K+ ions and then add 0.15 M KCl ions (49 K+ and 49 Cl-) in the system?

Thanks a lot!..

Nidhin Thomas