[gmx-users] dihedral problem - Coarse-grained graphene sheet

[Sajjad Kavyani]

Dear experts,
I want to simulate a graphene sheet with MARTINI force field. (In MARTINI
FF, the banzene is represented with 3 beads)
The problem I encountered with is the dihedral parameter.
I searched papers and found that the dihedral parameters for the sheet are
K=3.1, n=2 and phi =180.

The itp and the gro which I used both are in the zip-file below:

https://drive.google.com/open?id=0B8rMZ-61IzIWQS0tTTE1Qk9aM28

It is noteworthy that I tried both dihedral type
3   6.200     0.000     -6.200    0.000     0.000     0.000
and
1     180.00   3.1      2

but the forces are high because of the parameters at the end of EM runs.

Could you please help me how to place the parameter in the topology? and
what should order of indices be? Is they correct at all?

Regards