[lammps-users] Whole system is moving together towards x-axis of the simulation box

Dear Lammps-users,
I am running a repulsive system at low temperature and high density in 2D. After long enough simulation run, the whole system are moving together towards right-side of x-axis of simulation. I have also set velocity zero all linear and angular.
Kindly assist me here to fix the system moving together along right-side of x-axis of the simulation box.
I have Lammps 10-March 2021 version on ubuntu 20.04 LTS.

Thanking you

The velocity command is only removing the center of mass momentum once. You should apply it (with the scale, not create option) again later after the system is almost equilibrated. That usually does the trick.

If not you have to check your system setup for any imbalanced net forces or similar and correct. If that also fails you can think about using fix momentum to regularly (but infrequently) remove the center of mass momentum or use fix spring to apply a very weak restrain.


Dear Sir,
Thank you for the hand. Fix momentum command did the job for me.