(142u) Equilibrium and Non-Equilibrium Dynamics and Structure of Soft Sphere Fluids

We perform equilibrium and non-equilibrium molecular dynamics to study transport properties and structure of soft sphere fluids. The soft spheres are modeled using inverse power potential (v(r) = ε(σ/r)^-n) with n varied from 4 to 36. For equilibrium simulation, diffusion coefficient is computed based on mean squared displacement and viscosity is calculated according to the Green Kubo relation. We scaled the density with the freezing density for systems with different softness. This scaling law effectively collapses diffusion coefficient and viscosity from n = 6 up to 36, with n = 4 slightly deviating from our scaled curve. For non-equilibrium simulation, SLLOD algorithm is applied to simulate the simple shear flow. Systems with different softness are studied at the same scaled density. Shear viscosity and two-body translational structural order parameter are examined. The strong correlation between shear viscosity and translational structure order is found. Also this kind relation is dependent on the softness of spheres interaction. A close investigation of cumulative order integral illustrates the relation between shearing, softness and structure ordering.