[gmx-users] atom types IP and IM

[mohammad r]

Hi;
 I've used ff14sbamber force field to generate my system. As this force field doesn'texist in gromacs, I generated the first structure of my system withamber tools then I converted the topology and coordinate files intogromacs format by using acpype. (In the amber tools I've added NaClto my system). Now in the converted topology file I have these lines:
[ moleculetype ] ; molname nrexcl NA+ 1
[ atoms ] ; id_ at typeres nr residu name at name cg nr charge mass 1 IP 1 NA+ NA+ 1 1 22.9898
[ moleculetype ] ; molname nrexcl CL- 1
[ atoms ] ; id_ at typeres nr residu name at name cg nr charge mass 1 IM 1 CL- CL- 1 -1 35.45300
As we can see, wehave IP and IM atom types for Na+ and Cl- ions respectively. When Iwant to run energy minimization with the grompp command I get thiserror:
Fatal error: Atomtype IP not found For more information and tips for troubleshooting, please check the GROMACS  website at http://www.gromacs.org/Documentation/Errors
I think that itcannot recognize IP atom type. What should I do?
Thank you, Mohammad