A perturbation theory for solvation thermodynamics: Dipolar-quadrupolar liquids

The thermodynamics of solvation of a dipole in hard sphere solvents with di poles and quadrupoles is studied by using the Pade approximation for the pe rturbation expansion of the solvation chemical potential and compared to Mo nte Carlo simulations. Solvation chemical potentials, energies, and entropi es of solvation are obtained at different dipolar and quadrupolar solvent s trengths. The effect of nonlinear solvation is analyzed and found not to ex ceed 10% in the parameter range studied. An agreement between the simulatio ns and the analytical theory is obtained by an empirical rescaling of the t riple perturbation integrals of the perturbation expansion. This rescaling does not, however, provide a quantitatively correct partitioning of the sol vation free energy into the energy and entropy of solvation. (C) 1999 Ameri can Institute of Physics. [S0021-9606(99)51531-6].