MD simulation without using thermostat

Dear LAMMPS developers.

How to do MD simulation without using thermostat. I have a square graphene sheet (dimension x=y=100A to x=y=-100). I need to set high temperature at strip thickness 10A (x=90 to 100) and low temperature at strip 10A (x=-90 to -100). I able to simulate strip temperature with NVT. But in between the strips, i need to establish a thermal gradient without using thermostat.
Please suggest me suitable fix commend to do md simulation without thermostat. Similar simulation methodology has employed in the reference ( https://pubs.acs.org/doi/abs/10.1021/ct400963d ).

Thanks
with regards
SUNIL

Dear LAMMPS developers.

How to do MD simulation without using thermostat. I have a square graphene sheet (dimension x=y=100A to x=y=-100). I need to set high temperature at strip thickness 10A (x=90 to 100) and low temperature at strip 10A (x=-90 to -100). I able to simulate strip temperature with NVT. But in between the strips, i need to establish a thermal gradient without using thermostat.
Please suggest me suitable fix commend to do md simulation without thermostat. Similar simulation methodology has employed in the reference ( https://pubs.acs.org/doi/abs/10.1021/ct400963d ).

just use fix nve on those atoms. the gradient should form naturally during equilibration.
it is more common to use fix nve on all atoms and then fix langevin to thermalize both, the heat source and heat sink regions.

axel.

thankyou
With regards
SUNIL