Transient time correlation function calculation of the viscosity of a molecular fluid at low shear rates: a comparison of stress tensors

Shear viscosity of n-decane was computed using the molecular stress transient time correlation function (TTCF) formalism for the wide range of shear rates from 1.7 10 s 1 to 2.13 10 s . In earlier work calculations were presented for the shear viscosity of n-decane using the atomic stress formalism of the TTCF method (G. Pan and C. McCabe, J. Chem. Phys. 125(19), 4527 (2006)) in which we were able to close the gap between the lowest shear rates accessible by direct nonequilibrium molecular dynamics (NEMD) simulations and the highest shear rates possible in experimental studies. Here it is shown that the application of the molecular stress approach within the TTCF formalism, as an alternative to the atomic stress method, significantly reduces the number of NEMD trajectories necessary to obtain the shear viscosity.