[gmx-users] Calculate the forces from AFM pulling

[George Patargias DPhil]

Hello

I guess this is basic. Does anyone know how we can calculate
the forces from an AFM pulling run with Gromacs 3.2.1?

In the .pdo file we have the position of the pulled group (z_group)
and the position of the spring (z_spring). So the force exerted on
the pulled group is F = k*(z_spring - z_group)? Am I correct?
And is there a minus sign in this formula or not?

Thanks.
George