Viscosity, thermal conductivity and self-diffusion coefficient of the Lennard-Jones spline fluid: Evaluation of theories for a short-ranged potential

The Lennard-Jones/spline (LJ/s) potential is truncated and splined such that the potential and its first derivative continuously approach zero at $\approx 1.74\sigma$, making it short-ranged. In this work, we present a systematic study of the thermal conductivity, shear viscosity, and self-diffusion coefficient of the LJ/s fluid. Four theories are evaluated by comparing to results from equilibrium and non-equilibrium molecular dynamics simulations for temperatures in the range $0.7\le T^{\ast }\le 10$ and densities in the range $0.1\le {\rho }^{\ast }\le 0.8$. After regressing two parameters for each transport property in extended corresponding state theory with argon as reference fluid, the Average Absolute Relative Deviations (AARDs) with respect to the simulation data are 4.7% and 2.8% for the viscosity and thermal conductivity respectively. Using 4-6 regression parameters, residual entropy scaling yields AARDs of 5.7%, 2.6%, and 2.5% for the viscosity, thermal conductivity and self-diffusion coefficient respectively. A new method called corresponding entropic states theory is presented, which combines the concept of entropy scaling with the extended corresponding states formalism. Without any fitting parameters and with argon as reference fluid, the viscosity and thermal conductivity from the method have AARDs of 5.2% and 2.6%. For residual entropy scaling, extended corresponding states, and corresponding entropic states, the largest deviations are for the viscosity near the critical point, which can be explained by inaccuracies in the equation of state. Revised Enskog Theory, which is fully predictive, gives AARDs below 10% for $T^{\ast }\ge 3$, up to ${\rho }^{\ast }=0.4$. More work is needed to increase the accuracy of Revised Enskog theory at lower temperatures and higher densities.