[lammps-users] Boundary Condition

Hey Steve,
I am a bit confused of the boundary command, keyword f and s.
"For style s, the position of the face is set so as to encompass the atoms in that dimension (shrink-wrapping),
no matter how far they move.
For style m, shrink-wrapping occurs, but is bounded by the value specified in the data or restart file or set by the create_box command. "

I think I got the idea pretty much.
My understanding for style s is that no matter how much I stretch or compress the materials( atoms ), they will be kept
inside the simulation box. For style m, the minimum and maximum limits are set beyond which atoms lost may happen.

Just do not understand word “shrink-wrapping”, what’s the physical indication here ?

Hi Wen,
Based on my knowledge we use “s” type boundary condition to avoid any loss of atoms from your simulation domain. Lets say you have a N number of particles in a box and you shake the box, if you have top open then atoms can jump out of the simulation domain, using shrink wrapping boundary condition avoid any escape of atoms from the domain and your total number of particles remains constant. I used this boundary condition for a similar research problem in past.


Shrink-wrapping means the box size adjusts to just bound
the atoms, wherever they move to.