[gmx-users] how to calculate the force between two groups

[Tom]

Dear Gromacs Users,

I have a question about how to ouput the force between two groups.

Suppose the system consists of the groups: A, B, C and D.
I need the force only between the groups A and B.

g_traj looks only to be able to report the overal forces and cann not distiguish
the forces from different groups.

Is there any cunning way to do it.

Thanks,

Tom