[lammps-users] Velocity command for "LJ" units

Dear users
I am trying to set a fixed velocity for a group of atoms, where the units are “lj” and atom style is “granular” with the following command

velocity bottom set -3.0 0.0 0.0

when i run lammps, it says that “ERROR: Use of velocity with undefined lattice”

as i am reading the positions of particles through a read_data command and the length scale in this system is particle diameter, so i don’t need to define lattice

does the “Velocity” command works only for the systems where units are “lattice” or “real” ?

thanks and regards

append units box in the command.
This which move your group with the velocity of -3 sigma/tau in LJ units.