Using fix wall/region

Dear LAMMPS users,

I am trying to set up a box with two thin regions fixed as wall but I get
the error message below:
* ERROR on proc 24: Particle outside surface of region used in fix
wall/region (../fix_wall_region.cpp:245)*

I started the simulation by setting up 4 different cells and then combining
all the cells to form a single simulation box using the read_data command.
2 smaller cells of the 4 are intended to be walls to prevent interaction
between the 2 larger cells--I specified periodic boundary condition in all
the set-ups.

I understand that there may have been overlapping of particles at the
surface of the wall/region, as such, I specified regions to differ by
epsilon in their positions as suggested in the LAMMPS manual but the error
persisted. I would be glad if anyone can kindly help.

Attached is my input text.

Victor Fabiyi

MERGE_box.txt (1.47 KB)

there isn’t much that can be done from the outside.
you should carefully visualize your system and rather than piecing together all files at the same time, add them step by step.

a good check of whether regions overlap with atoms is also the delete_atoms command.
finally, with surfaces, you have to watch out for the “side in” versus “side out” option. sometimes it is not what you expect. again, delete_atoms can be very helpful to determine what is what.


Thanks, I will do that.