[lammps-users] Question about "boundary" command

Dear all,

I have a question about “boundary” command.

I would like to apply PBC only to X and Y directions.
When I set 'boundary p p f ’ or ‘boundary p p p’, it works well for my simulation system where I put something in a vacuum box.

But If I change it to “boundary p p s”, The process is killed with information that
" Rank 0, Process 22491 received signal SIGSEGV(11)
MPI: --------stack traceback-------

Why? Besides, can someone explain the difference between “f” and “s” in this command. I am not clear about the instruction in MANUAL.Thanks.

Happy new year to you guys.

Dear Jarvis,
The style “f” for the boundary command will put a face or wall at given desired location (which is previously fixed by user), whereas in style “s” the position of face is not fixed and the whole domain in that specific direction can move or extend to avoid any atom loss from your domain.

One of the example in which you can use style “s” if you have a opening in your domain but you want to avoid any atom loss from that opening so you will put style “s” in that direction with wall position “NULL” and the domain will extend in that direction to encompass all atoms in that direction.


Normally, f or s should work similarly, though f will allow
atoms to be lost if they move beyond the boundary. I'd
have to know more about what your simulation is doing
to say why the s case crashed.