Comment on "Relationship between McQuarrie and Helfand equations for the determination of shear viscosity from equilibrium molecular dynamics"

In a recent paper, Chialvo, Cummings and Evans Phys. for the calculation of shear viscosities in molecular dynamics simulations. We point out that their analysis does not correspond to the simulation algorithm they actually use, that the system-size dependence they derive and the extrapolation procedure they propose are incorrect, and that they have established no relation between their analysis and the shear viscosity. Our own analysis explains the simulation results in terms of the artiicial way that periodic box boundary crossings are handled. We nd no support for a link between the McQuarrie formula and any valid statistical mechanical expression for the shear viscosity.