Force calculation "fix rigid" vs "compute group/group"

Hi all,

In my simulation I have formed a spherical rigid body which contains a number of particles. The force that I get from fix rigid is exactly N times (N being the number of all atoms in my system) greater than what I get from “compute group/group” for the rigid body group from the rest of the field. Based on what I understand from the manual they should be the same, right? but I don’t know how this constant factor (N = number of atoms in the system) shows up there. I’d appreciate your comments on this.

Thank you,

Two questions:

a) have you tried dumping the force on each atom in your body
in a dump file and inspecting the values (or summing them) yourself?

b) how are you outputting the 2 values you mention - it could be that
thermo output is normalizing one of them, depending on your
setting for thermo_modify norm.


Thank you Steve, that was just normalizing in thermo_modify.