Non Periodic System

I am simulating a system periodic in x and y direction and non periodic in z direction
As a system with non-periodic boundaries always represents an infinite volume

Which ensemble should be used NVT/NPT to begin with ? I want to heat the system by first equilibrating it at a particular temperature and then begin heating.

I am simulating a system periodic in x and y direction and non periodic in z
direction
As a system with non-periodic boundaries always represents an infinite
volume
Which ensemble should be used NVT/NPT to begin with ? I want to heat the
system by first equilibrating it at a particular temperature and then begin
heating.

two comments:

1) since this is more a question about how to best conduct MD
simulations rather than about specific LAMMPS features, you should be
aware, that this is somewhat off-topic for this list.
2) there are probably as many opinions about what is "the right
way(tm)" to do equilibration and specifics of simulation workflows.
you'll find plenty of descriptions about the applied procedures in the
available published literature (at least in the well written papers)
and also many, many discussions in the mailing list archives. please
help yourself to this vast pool of available knowledge and opinions.

axel.