I think either using periodic boundary condition or you have to write a new script for WS defect analysis in Ovito.
I use periodic boundary conditions in all directions. However, my simulation box is larger (in the z direction) than the crystal in order to leave some space for the projectile that comes from outside as it is an external irradiation.
I do not know another way to do it.
If I could use a simulation box with ppp conditions with the same size as the crystal, it would avoid the expansion, I do agree. But how to do with the projectile that must start from outside?
I think your should do the simulation however makes sense in LAMMPS.
The WS issue is more a Q about Ovito. You can see if it has a mail
list or email the author.
I already contacted him. He gave me an article where they perform a cleaning to reposition atoms that could have moved by expansion of the material during the cascade, before using the a WS.