[gmx-users] genbox nmol add water

[martin sippel]

Dear all,

how can I manage to put a certain number of water molecules in a box? I 
tried the genbox -nmol option with -ci spc216.gro, but it didn't work 
out due to "more than one residue". Can I convert the spc216.gro file so 
that it'll contain only one residue (and how) or is there a better way? 
I need to have the same number of molecules in a box, if I want to do 
free energy calculations, right?
Thanks in advance for any support!

Bye,

Martin