Solvation free energy calculation in Forcite

Hi all,

 

I want to calculate the solvation free energy of a cation in water using Forcite.

 

In this case, do I make the initial cell with only cation and water, or do I need to put an anion to make the cell neutral?

Also, how can I know if the equilibration step and production step are long enough to obtain the equilibrated state?

 

Thank you!!