Question about the command fix indent sphere

Hi everybody,
I have a question about the command “fix indent sphere”. I’m doing the simulation of amorphous polymer, and I want to create a cavity in the center of the system (to insert the nanoparticle) (this idea was introduced in a thread before). I think there should be a velocity de creation inorder not to disrupt the polymer system, and certainly the constant K (is reasonably choosen) (based depending on the system). As indicated in the fix indent, I know that it is possible to take all 4 quantities “x0 y0 z0 r” into variables. I have some questions:
1 - Should I create cavity after the system has reached the equilibrium, or at the same time with simulation? (in my system, the volume of the simulation box changes after the equilibrium, so the center of the indenter will changes correspondingly)
2 - If I want r becomes a variable , depends on r0, velocity, step, dt (as in the tutorial), (what’s different between step in dt here?), then how to select the desired radius (final) of the cavity?

Those are conceptual Qs, not really LAMMPS Qs.
LAMMPS will let you insert the cavity and grow it
into place however you wish. It’s up to you to
decide what is best for your model, and to expt
with different methods of doing it to see
what works reasonably.