Mean spherical approximation for the Lennard-Jones-like two Yukawa model: Comparison against Monte Carlo data

Monte Carlo simulation studies are performed for the Lennard-Jones-like two Yukawa (LJ2Y) potential to show how properties of this model fluid depend on the replacement of soft repulsion by hard-core repulsion.Different distances for the positioning of hard-core have been explored.We have found that for temperatures slightly lower and slightly higher than the critical point temperature for the Lennard-Jones fluid, the placement of the hard-core at distances shorter than zero-potential energy is well justified by thermodynamic properties that are practically the same as in the original LJ2Y model without hard-core.However, going to extreme conditions with the high temperature one should be careful since the presence of the hard-core provokes changes in the properties of the system.The later is extremely important when the mean-spherical approximation (MSA) theory is applied to the treatment of the Lennard-Jones-like fluid.