The solution of the hypernetted-chain approximation for fluids of nonspherical particles. A general method with application to dipolar hard spheres

In this paper we describe a general method for the numerical solution of the full hypernetted-chain (HNC) theory for fluids characterized by angle-dependent pair potentials. This method is also applicable to the closely related reference hypernetted-chain (RHNC) approximation. The only formal restriction is that the pair potential and correlation functions must be expandable in a basis set of rotational invariants. We present explicit numerical solutions of the RHNC theory for dense dipolar hard sphere fluids and detailed comparisons are made with previous theories and computer simulation results. It is found that the full RHNC theory generally improves upon the previous reference linearized and quadratic HNC approximations. The values given by the RHNC theory for the static dielectric constants are smaller than those given by these earlier approximations and are in much better agreement with computer simulations.