  We studied the connection between the structural relaxation and viscosity for
a binary model of repulsive particles in the supercooled liquid regime. The
used approach is based on the decomposition of the macroscopic Green-Kubo
stress correlation function into the correlation functions between the atomic
level stresses. Previously we used the approach to study an iron-like single
component system of particles. The role of vibrational motion has been
addressed through the demonstration of the relationship between viscosity and
the shear waves propagating over large distances. In our previous
considerations, however, we did not discuss the role of the structural
relaxation. Here we suggest that the contribution to viscosity from the
structural relaxation can be taken into account through the consideration of
the contribution from the atomic stress auto-correlation term only. This
conclusion, however, does not mean that only the auto-correlation term
represents the contribution to viscosity from the structural relaxation.
Previously the role of the structural relaxation for viscosity has been
addressed through the considerations of the transitions between inherent
structures and within the mode-coupling theory by other authors. In the present
work, we study the structural relaxation through the considerations of the
parent liquid and the atomic level stress correlations in it. The comparison
with the results obtained on the inherent structures also is made. Our results
suggest that in the supercooled liquid regime the vibrational contribution to
viscosity extends over the times which are much larger than the Einstein's
vibrational period and much larger than the times which it takes for the shear
waves to propagate over the model systems. Besides addressing the atomic level
shear stress correlations, we also studied correlations between the atomic
level pressure elements.

Materials Science;Soft Condensed Matter