Is a negative pressure correct in reax/c?

Dear lammps users,

Hello everybody

I’m working with reax/c package on lammps. I had made a simple input example in gaseous phase as below:

1 C60(NO2)12 + 12 O2 molecules = 126 atoms

Cubic simulation box with a= 24.81 angestrom

With the below input file:

Yes, of course. Pressure values can be positive or negative, and negative pressure value just indicates the system wants to contract. There is nothing wrong with it.

I highly recommend you read some classic MD text books: Allen & Tildesley on Computer Simulations of Liquids, and Frenkel & Smit on Understanding Molecular Simulations. You can find pdf versions online.



Yes, it fluctuates around an average (at equilibrium), and smaller systems can have quite large fluctuations. A 126 atom system is very small.