Evaluation of angular correlation parameters and the dielectric constant in the RISM approximation

We prove, using a projection operator method, a number of results obtained when site-site correlation functions are evaluated in the RISM approximation. In non-polar fluids, the angular correlation parameter G 2 is identically zero for any symmetric linear molecule, while G 1 is identically zero for an arbitrary linear molecule. In rigid polar fluids, the dielectric constant є is found to be given by the ideal-gas type expression є = 1 + 3y, where y = 4πβρμ2/9.