Nonequilibrium molecular dynamics simulations are reported at different strain rates $\left(\dot{\gamma }\right)$ and thermodynamic state points for a shearing atomic fluid interacting via a Lennard-Jones potential. Our simulations are performed at the Lennard-Jones triple point, a point midway between the triple point and the critical point, and a high point closer to the critical temperature. We find that, for the mid-point and high point, the energy and hydrostatic pressures have strain-rate dependencies of ${\dot{\gamma }}^2,$ in contrast to the ${\dot{\gamma }}^{3/2}$ dependencies predicted by mode coupling theory. This analytical dependence is consistent with a Taylor series expansion of these quantities as powers of the strain rate tensor. Only at the triple point does the pressure and energy display a nonanalytical dependence on ${\dot{\gamma }}^{3/2}.$

• Received 28 February 2001

DOI:https://doi.org/10.1103/PhysRevE.64.021201