A statistical mechanics/density functional approach to the thermodynamics of liquids

This study describes an accurate partition function obtained evaluating the configurational integral of molecular solutes with a computationally feasi ble method. The key features of this method include the partition function' s factors for translation (calculated according to the approach of the Lenn ard-Jones-Devonshire theory of liquids) and libration. The proposed molecul ar partition function has been successfully tested computing entropies of v aporization and molar heat capacities at constant volume for the four commo n liquids dichloromethane, acetonitrile, methanol, and water. The formulati on of pressure-dependent properties is also given through a virial equation , and the evaluation of its simplest term allows the estimate of enthalpies of vaporization. Structural parameters needed by the theory, such as bindi ng energies of particles to the bulk, have been obtained through density fu nctional theory calculations on monomers, dimers, and clusters of the four test liquids. (C) 2001 American Institute of Physics.