[lammps-users] planeforce vs. setforce

Dear all,

I appreciate it if someone can explain the possible differences in results by using one of the following fixes in a system. Do we get the same results by keeping other things the same in minimization or a dynamic run?



“fix 1 all planeforce 1.0 0.0 0.0”


“fix 1 all setforce 0.0 NULL NULL”

yes, I think the 2 commands will do the same thing. At least conceptually, maybe not numerically in the sense
of there being round-off which means 2 sims could diverge after many timesteps. You should test this yourself by
dumping out the forces for each atom and comparing the 2 dump files. Likewise comparing the thermodynamic output
every step to high precision.