Local density enhancement in neat supercritical fluids: dependence on the interaction potential

We study the local structural properties of neat supercritical fluids. Three forms of intermolecular potentials are considered – Lennard-Jones, Morse, and Stillinger-Weber. The inhomogeneous integral equation theory is employed to compute the local coordination number of a tagged solvent particle. The theory is shown to be in excellent agreement with the simulation for all intermolecular potentials throughout the entire density range. The degree of local density augmentation in neat supercritical fluids is shown to be sensitive to the details of intermolecular potential, with a particular important parameter being the ratio of the potential well-depth to the critical temperature of the fluid.