Structure and thermodynamics of the dipolar hard sphere fluid from the reference-hypernetted chain equation with minimized free energy
F. Lado, M. Lombardero, E. Enciso, S. Lago, and J. L. F. Abascal
J. Chem. Phys. 85, 2916 (1986)
ABSTRACT
The reference-hypernetted chain equation, generalized to molecular fluids, is optimized by choosing the reference system so as to minimize the free energy. This procedure, which assures a significant improvement in the internal thermodynamic consistency of the theory, is here applied to a fluid of dipolar hard spheres, using both the complete dipolar potential and one with a reaction field (RF) truncation. We confirm that a recent reformulation of the relation between the dielectric constant and the mean square dipole moment for the RF geometry indeed brings for the truncated potential into reasonably good agreement with the infinite-range values, but that the important correlation functions nevertheless differ qualitatively in their long-range behavior. The method of solving the molecular integral equation, developed earlier, can be applied to other multipolar potentials, or alternatively, to molecules with distributed point charges.
