Thermodynamical, structural, and dielectric properties of molecular liquids from integral equation theories and from simulations

A survey is given on our attempts to calculate equilibrium properties of molecular liquids (pure solvents and electrolyte solutions) with the help of spatial pair correlation functions, starting from classical molecular pair interactions. The selection of potential models, especially the influence of molecular polarizability, is discussed as well as the limitations of the different methods of calculation of molecular pair correlation functions (e.g., from molecular and site-site Ornstein-Zernike theories, from Monte Carlo and from molecular dynamics simulations). We have performed simulations and integral equation calculations for spatial distribution functions in pure solvents with very low dielectric constants as dioxane and tetrahydrofuran, up to solvents with a very high dielectric constant like n-methylformamide. Ionic solvation is studied in pure solvent systems as well as in solvent mixtures. The general features of ion solvation and association, of the solvent structure around solutes, and their influence on solution properties, are discussed in the framework of the different theoretical approaches.