Problem with temperature in NVT

Dear Lammps community:

I am using LAMMPS (7 Aug 2019). Here I want to prepare my system at the desired temperature 1000K. Using the following command, the system temperature is oscillated and never reaches 800 K. Anyone has a suggestion on this? Thanks in advance.


there is not enough information about the kind of system you are simulating to make any definite statements.

in general, it would be better to use a dissipative thermostat like fix langevin at the beginning of equilibration if your system is far from equilibrium (e.g. needs to be melted). also, in such cases, you can assign a much higher initial temperature, as up to half of the kinetic energy will be converted into potential energy during equilibration.

also, 10000 MD steps is not a lot for equilibrating all but the most trivial systems.


Thanks very much for your reply.

I want to prepare the Fe surface slab at the desired 1000 K. Firstly, I minimize the system. Then I used FIX NVT for 1000 K sampling. Since the “DRAG” option may change the distribution of velocity and position, I use firstly 2000 steps for FIX NVT with DRAG, followed by a FIX NVT without DRAG for another 1000 steps. I hope this way the velocity and position are correct, namely, corresponding to 1000 K. Is this way suitable?

Thanks. See also below for detailed input commands.