FRQ: Stress tensor and mechanical pressure.

[hechtprojects]

Proposed new feature or change:

The (local) stress tensor can easily be calculated from simulation data using the Irving-Kirkwood stress tensor [1]. It can also be applied to non-equilibrium systems as shown in Ref. [2] (see Eq. 2). From the stress tensor, one can then calculate the mechanical pressure from its trace.

We should add this feature (stress tensor and pressure calculation) to AMEP's thermo module.

[1] https://pubs.aip.org/aip/jcp/article/18/6/817/201367/The-Statistical-Mechanical-Theory-of-Transport
[2] https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.168201