how lammps calculate force with the force is set as NULL

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1

Hi lammps users
After read the Pseudo-code in developer guide which explains how the Verlet:run () method works. I have a question about how lammps calculates the force when fix setforce command is used. As stated in developer guide, the MD force is computed by the methods from pair->compute () to kspace->compute (). While the fix->post_force () method deals with the external force. If the following command is used

fix 2 flexible_wall setforce 0.0 NULL NULL

I think lammps will set the force in x direction as 0. While the force components in y,z direction should same as the MD force which is calculated by the methods from pair->compute () to kspace->compute ().

Is that right?

Fan Li

2

Hi lammps users
After read the Pseudo-code in developer guide which explains how the
Verlet:run () method works. I have a question about how lammps calculates
the force when fix setforce command is used. As stated in developer guide,
the MD force is computed by the methods from pair->compute () to
kspace->compute (). While the fix->post_force () method deals with the
external force. If the following command is used

fix 2 flexible_wall setforce 0.0 NULL NULL

I think lammps will set the force in x direction as 0. While the force
components in y,z direction should same as the MD force which is calculated
by the methods from pair->compute () to kspace->compute ().

Is that right?

yes.