Hi everyone,
The equivalence of Virial stress in LAMMPS and Mechanical Stress (Cauchy Stress) is so controversial in the literature. My concern is to get the mechanical stress. Some say that The Kinetic Energy (KE) term should be excluded from the virial stress and others say that it shouldn’t. If anyone has an excellent final conclusion, please let me know.
Anyway, I’ve a couple of questions regarding the theory of the virial stress in LAMMPS;
When periodic boundary conditions is employed but atoms don’t cross any of the sides of the simulation box, does that mean that Lagrangian frame of reference is employed implicitly in lammps or there’s another way to activate that reference?
When temperature increases and LJ potential is used, how does that affect the virial stress and LJ potential is temperature independent?
Thanks in advance!
You can exclude the kinetic term in either the global
stress (compute pressure) or per-atom stress (compute stress/atom).
There is no conceptual difference between a periodic or non-periodic
system in how LAMMPS calculates the virial, other than what is
used as the volume of the system.
When temperature increases and LJ potential is used, how does that affect the virial stress and LJ potential is >temperature independent?
You can test this yourself by running simulations.
Steve
hello
i obtain information from this article.
http://www.sciencedirect.com/science/article/pii/S0020768308001248
king regards
You can exclude the kinetic term in either the global
stress (compute pressure) or per-atom stress (compute stress/atom).
There is no conceptual difference between a periodic or non-periodic
system in how LAMMPS calculates the virial, other than what is
used as the volume of the system.
When temperature increases and LJ potential is used, how does that affect the virial stress and LJ potential is >temperature independent?
You can test this yourself by running simulations.
Steve