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 the soft repulsion by the hard-core repulsion. Different
distances for the positioning of hard core have been explored. We have found,
that for temperatures that are slightly lower and slightly higher of the
critical point temperature for the Lennard-Jones fluid, placing the hard core
at distances that are shorter than zero-potential energy is well justified by
thermodynamic properties that are practically the same as in original LJ2Y
model without hard core. However, going to extreme conditions with the high
temperature one should be careful since 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 treat the
Lennard-Jones-like fluid.Comment: 11 pages, 13 figure