  A theoretical study on the equation of state and the critical point behavior
of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation
theory, restricted to first order in the inverse temperature and having the
hard-sphere fluid as the reference system, is used to derive a relatively
simple analytical equation of state of hard-core multi-Yukawa fluids. Using
such an equation of state, the compressibility factor and phase behavior of six
representative hard-core double-Yukawa fluids is examined and compared with
available simulation results. The effect of varying the parameters of the
hard-core double-Yukawa intermolecular potential on the location of the
critical point is also analyzed using different perspectives. The relevance of
this analysis for fluids whose molecules interact with realistic potentials is
also pointed out.
