STUDIES ON FREE-ENERGY CALCULATIONS .2. A THEORETICAL APPROACH TO MOLECULAR SOLVATION

Using the concepts of scaled particle theory, an analytical theory is developed to investigate the Limiting behavior of solvation free energ ies at the particle creation limit. The new theory directly incorporat es the weakly attractive, dispersion interaction terms into the analyt ical calculations. For neutral molecular systems, the effects of longe r ranged electrostatic interactions are also incorporated, albeit in a n ad hoc way, and the validity of the utilized assumptions are then de monstrated with numerical examples. It is shown that it is possible to blend the numerical and analytical methods to increase the reliabilit y of quantitative results, and, at the same time, to achieve savings o n computational expenditure for certain types of calculations. Differe nt methods of performing the thermodynamic integration in solvation fr ee energy calculations are also compared. Studied examples clearly sho w the importance of proper treatment of the divergence at the particle creation limit in obtaining quantitatively reliable results for the s olvation free energies.