Strange pressure with Lennard Jones system

Dear Lammps users, I have a question about the "melt" example of LAMMPS; in particular, I am confused about the pressure output values.
I am running the example input script (inside "share/lammps/examples/melt"), and I am adding the tail corrections too (via pair_modify tail yes)... now, the program generates pressure values P* around 6, which correspond to more or less 2500 atmospheres for Argon... and this value seems to me to be totally non-sense!
The temperature is a much more reasonable value of T* = 1.5 (180 K for Argon). The simulation is run at a reduced density of 0.8442.

What is wrong with that? What information am I missing?
The only other parameter I have changed, with respect to the original input script, is the total number of steps (from 250 to 10000).

Thanks in advance and greetings for the New Year,

Francesco Mambretti

Please note that the melt example is just that: an example. It’s just some starting configuration that runs for a few time steps. If you want to obtain thermodynamic properties you’ll need to properly equilibrate the system at the desired conditions.


I’ll add that a T* = 1.5, which is high, it’s likely
that a large component of the pressure is kinetic.
You can use the compute pressure command with
various keywords to see which components are
contributing to the 6.0 value.