Hello,
I am running a simulation to simulate the depression of a membrane. I want to get force vs. displacement data for a group (all groups use the same AIREBO potential), but I have difficulty calculating the force. Here is how I have tried to calculate force:

compute stress/atom, with a reduce to sum and average and divide by the “volume” of the group of atoms I am interested in. My main problem here is the volume calculation. The forces reported by this method seem to be off (by orders of magnitude), I estimate the volume of the group by taking the volume of the entire ensemble (vol), and multiplying it by a factor that corresponds to the portion of the space occupied by the group I am interested in. It should be noted that I have shrinkwrap boundary conditions, so I believe my simulation box is growing with the membrane as it deforms.

compute group/group, does not work with AIREBO is there any way to get it to work? Is there an analogous method?
Any suggestions are welcome. Thank you,
Emil