[gmx-users] [pairs] directive issue

Tsjerk Wassenaar tsjerkw at gmail.com
Sat May 9 09:28:02 CEST 2015

Hi Raja,

[ pairs ] is a molecule level directive and so has to fall under a [
moleculetype ] directive. If you want to add pair types based on atom
types, similar to [ bondtypes ], you'll have to use... [ pairtypes ]

Try to get hold of the force field lay out if you're tampering with
parameters. Check the manual.


On May 9, 2015 07:21, "Raj D" <gromacs.for.f at gmail.com> wrote:

> Dear Users,
> I am introducing a new ff for a small molecule in the Amber forcefield , I
> have itp file for the new molecule ( by antechamber ) and uses RB potential
> for proper dihedrals and so tried to copy and paste [ pairs ] directive
> from itp file to ffbonded.itp but grompp run reports invalid directive
> usage error and the location of the directive is after [ bondtypes]
> directive ....I don't know what is the cause of source of error and I also
> tried to move the [ pairs] directive to various locations in the file but
> the problem still persists. Please help me.
> Regards,
> Raja
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