Sign of per atom stress computed by LAMMPS

Hi,
I am using LAMMPS to perform coarse-grained particle dynamics simulations of biological cells and tissues. I am using LAMMPS version – 29 October 2020.

I am using compute stress/atom to find out the spatial distribution of stress inside the subcellular space. There is only pairwise interaction in my simulations because there are only non-bonded particles. What is the significance of the sign of the stress computed? Is it true that positive and negative values indicate tensile and compressive stresses, respectively? I am using Morse potential in my simulations.

Best regards,
Sandipan

When the (total) pressure (not stress) of a system is negative, it “wants” to shrink, if it is positive, the system “wants” to expand. The documentation of compute stress/atom shows how to compute this pressure. I leave the conclusions to you.