IN SEARCH OF A THERMODYNAMICALLY SELF-CONSISTENT INTEGRAL-EQUATION FOR LINEAR MOLECULAR FLUIDS

We present a first exploratory attempt to build a closure relation for molecular fluids which, relying on the structure of the reference hyp ernetted chain approximation fulfils the conditions of thermodynamic c onsistency between the virial and fluctuation routes to evaluate the p ressure. We report here results for two-centre Lennard-Jones fluids wi th and without embedded quadrupoles, which unequivocally show that a s imple approximation that accounts roughly for the angular dependence o f the bridge function plus the consistency criterion significantly imp roved upon the hypernetted chain equation results, particularly as far as thermodynamics is concerned.