I have some questions about the formulation for calculating the stress tensor, found under the compute stress/atom command. It is mainly the notation that confuses me. It seems quite different from other kind of notations, e.g. compared to the three paper mentioned in the manual.
For example, in the second term for pairwise interaction:
- The summation is over “n” which loops over the Np nearest neighbors, but there is no index “n” in the terms?
-The positions of the two atoms in the pairwise interaction are r1 and r2, but the position with respect to what? The origin (0,0,0) of the simulation box or the atom “i”?
- Is the pairwise interaction between atom “i” and it neighbors? Or is the pairwise interaction only between neighbors of atom “i” (meaning that atom “i” is not part of the sum)?
Is there any literature/papers where this formulation is documented/explained so I can read up about it?