I saved sxy,sxz,syz stress tensors/atom at every time step for a 100 time steps run. The purpose is to compare results from lammps with another software (written by my group-mate, which is 3 times slower). In his code he outputs sxy,sxz,syz stress tensors of the system (and not per atom) at every time step. Since, LAMMPS gives it per atom, how do I go about to get the stress tensors, sxy,sxz,syz of the system?
I have tried to add the contributions of all the atoms to obtain the corresponding component for the total system. But, there is a big difference in both the results. This tells me that there is something wrong in the way I calculate the tensor components of the system (from tensor components/atom). Please provide me with some help on this. It would be great if somebody could tell me the correct way.
Steve told me in his previous mail that the total pressure is the total stress when aptly normalized. But, thats not what I want. I want the tensor componets (sxy,sxz,syz) of the system.