  We derive the transient-time correlation function (TTCF) expression for the
computation of phase variables of inhomogenous confined atomistic fluids
undergoing boundary-driven planar shear (Couette) flow at constant pressure.
Using nonequilibrium molecular dynamics simulations, we then apply the TTCF
formalism to the computation of the shear stress and the slip velocity for
atomistic fluids at realistic low shear rates, in systems under constant
pressure and constant volume. We show that, compared to direct averaging of
multiple trajectories, the TTCF method dramatically improves the accuracy of
the results at low shear rates, and that it is suitable to investigate the
tribology and rheology of atomistically detailed confined fluids at realistic
flow rates.
