Structural and Thermodynamic Properties of Van der Waals Fluids via a Hard-Core Sutherland Potential

The structural and thermodynamic properties of the Van der Waals fluids are determined at a wide range of densities and temperatures. For this purpose, the second-order Barker and Henderson perturbation approach is used with an effective pair intermolecular interaction model involving a hard-core repulsion coupled with an attractive tail in the Sutherland function. A developed analytical expression for the radial distribution function of hard spheres is used to account for the reference fluid contribution. A good prediction is made for calculating the static structure factor S ( k ), Helmholtz free energy ( A ), compressibility factor ( Z ), and isothermal compressibility (κ T ) for the argon and nitrogen fluids. Furthermore, the calculated results are developed when the contribution of many-body interactions is accounted for using an effective pair potential in which its intermolecular parameters are dependent on the thermodynamic states.