HYPERNETTED AND REFERENCE HYPERNETTED CHAIN INTEGRAL-EQUATIONS FOR LENNARD-JONES DIATOMIC FLUIDS WITH QUADRUPOLAR INTERACTIONS

The hypernetted chain and reference hypernetted chain integral equatio ns are solved for quadrupolar two-center Lennard-Jones fluids and the computed fluid structure and thermodynamics are contrasted with comput er simulation. A reference bridge function is determined through an em pirical modification of Verlet's approximation. The resulting referenc e hypernetted chain equation leads to good agreement with simulation d ata. On the contrary, the bare hypernetted chain approximation perform s poorly, in particular as far as the equation of state is concerned, which is a well-known drawback of this closure when short ranged repul sive potentials come into play.