Molecular Insights into Transport Coefficients and the Stokes-Einstein Relation in Simple Liquids

We evaluated the thermodynamic-variable dependence of self-diffusion coefficient and viscosity in simple Lennard-Jones (LJ) liquids by using equilibrium molecular dynamics calculations. In order to consider the connectivity... [ view full abstract ]

We evaluated the thermodynamic-variable dependence of self-diffusion coefficient and viscosity in simple Lennard-Jones (LJ) liquids by using equilibrium molecular dynamics calculations. In order to consider the connectivity with hydrodynamic region, the transport properties of fullerene nano-particles in simple liquids was also investigated.   The self-diffusion coefficient and viscosity show the strong dependence on packing fraction, and moreover, only the self-diffusion coefficient depends on the differences of sizes, masses and interaction energies between solute and solvent.  These effects are significant for deriving the scaling equations in simple liquids over wide ranges of thermodynamic conditions.   The product of the obtained scaling equations implys that the Stokes-Einstein (SE) relation depends on packing fraction and the differences of masses and interaction energies between solute and solvent.   In particular, the term of interaction-energy ratio is dominant even for nanoparticles, which well correlates the decay time of solvation structure of solutes.  In the presentation, we'll demonstrate that these molecular effects account for the change of boundary condition in SE equation, and the differences between solute radius and the hydrodynamic one.