[gmx-users] A wired fatal error in grompp about ions

[Binbin Liu]

Dear all,

Since I dont know how to define K ion atomtype with the using of gromos96 ff, 
I tried to replace K by Na.

What I have done is that replaced K by Na in .gro, .top and .mdp. The wired 
thing is when I ran grompp. The program still keeps giveing the fatal error 
warning: Atomtype 'K' not found!.

By the way, does it really matter I use GROMOS96 ff (ff43*) rather than other 
force fields? 

Help! Thanks a lot!