[gmx-users] largest charge group

[Justin Lemkul]

On 12/30/19 2:53 AM, Maryam Sadeghi wrote:
> Dear All,
>
> I have created a coarse-grain (cg) structure of a polymer containing 49
> beads (the atomistic structure contains 193 atoms), each beads has a zero
> charge.
> I have created the .itp file manually, defining the atom types and the
> bonds  and angles (no dihedrals in my model). When I used GROMAC's grompp
> command, I get the following error:
>
> gmx grompp -f em.mdp -c cg_PCL_box.gro -p topol.top -o em.tpr -maxwarn 1
>
> Fatal error:
> The largest charge group contains 49 atoms. The maximum is 32.
> For more information and tips for troubleshooting, please check the GROMACS
> website at http://www.gromacs.org/Documentation/Errors
>
> Could anyone suggest how I can fix this problem? I will need to do
> simulations on longer chains as well.

Assign different residues/monomers to different charge groups. Your 
entire polymer is one group, which is not allowed.

-Justin

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Justin A. Lemkul, Ph.D.
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