  Recently there have been several considerations by different authors of
viscosity and the Green-Kubo stress correlation function from the microscopic
perspective. In most of these and earlier works the atomic level stress is the
minimal element of stress. It is also possible to consider, for pairwise
interaction potentials, as the minimal elements of stress, the stress tensors
associated with the pairs of interacting particles. From this perspective, the
atomic level stress is not the minimal stress element, but a sum of all pair
stress elements in which involved a selected particle. In this paper, we
consider the Green-Kubo stress correlation function from a microscopic
perspective using the stress tensors of interacting pairs as the basic stress
elements. The obtained results show the presence of a long-range
bond-orientational order in the studied model liquid and naturally elucidate
the connection of the bond-orientational order with viscosity. It turns out
that the long-range bond-orientational order is more clearly expressed in the
pairs' stress correlation function than in the atomic stress correlation
function. On the other hand, previously observed stress waves are much better
expressed in the atomic stress correlation functions. We also address the close
connection of our approach with the previous bond-orientational order
considerations. Finally, we consider the probability distributions for the
bond-stress and atomic stress correlation products at selected distances. The
character of the obtained probability distributions raises questions about the
meaning of the average correlation functions at large distances.
