Hi all,
I am trying to compress my model with wall commands in LAMMPS.

This is my code:

fix bottomwall all wall/harmonic xlo 45.0 1.0 1.0 2.5 units box

fix topwall all wall/harmonic xhi 115.0 1.0 1.0 2.5

variable linear equal vdisplace(0,20)

fix wallhi all wall/harmonic xlo v_linear 1.0 1.0 2.5

After running several steps I will get this error:

ERROR on proc 5: Particle on or inside fix wall surface (…/fix_wall_harmonic.cpp:65)

I have read this page in lammps mail list, but the link there is not working.

Also, I have attached my in* file file.

So can you please help me what should I do?

I really appreciate your help and time.

Best Regards,


in.compress (1.98 KB)

If a particle has moved inside the wall surface, then that is
bad dynamics. LAMMPS cannot compute a force
on that particle. since it is ill-defined. As the NOTE on
the doc page says, for wall/harmonic you must specify
a large enough epsilo (stiffness of spring)
such that particles stay on the correct side of the wall.