[lammps-users] To stop leakage of atoms from the bottom of slab

Respected Users,
I am melting a piece of iron metal on the surface of graphite using npt ensemble. After melting it on 1900k it oozes from lower surface as it seems that iron atoms are not physically contacting or feeling the physique of graphite atoms. So how to write a command for this problem.
Thanks for cooperation

Not enough info to say. I suggest using NVE to debug.