[gmx-users] Ionic liquid simulation problem

[Agatha Faria]

> Dear GROMACS Community,
> 
> I am very new with GROMACS I am trying to run a simulation of an ionic liquid (1-butyl-3-methyl-imidazolium and hexafluorophosphate) according to the following protocol:
> 
> 1. Prepared the respective PDB files and added/modified the OPLS/AA force field parameters updating the atomtypes.atp, aminoacid.rtp, ffbonded.itp and ffnonbonded.itp files.
> 
> 2. Used pdb2gmx command to create the respective .gro files, as well as, the posre.itp and topol.top files chossing OPLS/AA option without solvation.
> 
> 3. Used the insert-molecules command to create a box filled with one specie (cation) and add the other specie (anion) into the same box.
> 
> 4. Updated, by hand, the generated topol_box.top (pos_box.top) file including the topol.top and the posre.itp files of the other specie (anion) at the end of it.
> 
> 5. Tried to used the grompp command to minimize the energy of the cations+anions box and got the following error:
> 
> Fatal error:
> Too many warnings (18), gmx terminated.
> If you are sure all warnings are harmless, use the -maxwarn option.
> 
> 6. Using a -maxwarn option got the following error:
> 
> Error in user input:
> Invalid command-line options
> In command-line option -maxwarn
> Too few (valid) values
> 
> Does anyone knows whats is wrong with such a protocol?
> 
> Thanks in advance.
> 
> Ágatha
>