Shear stress correlations in hard and soft sphere fluids

Abstract

The shear stress autocorrelation function has been studied by molecular dynamics simulation using the q−n potential for very large n. The results are analysed and interpreted here by comparing them with the shear stress response function for hard spheres. It is shown that the hard sphere response function has a singular contribution, and that this is reproduced accurately by the simulations for large n. A simple model for the stress autocorrelation function at finite n is proposed, based on the required hard sphere limiting form.