POTENTIAL OF MEAN FORCE CALCULATION OF SOLUTE MOLECULES IN WATER BY AMODIFIED SOLVENT-ACCESSIBLE SURFACE METHOD

We propose an empirical method for evaluating the potential of mean fo rce (pmf) of solute molecules in water by modifying the solvent-access ible surface (SAS) method described by Eisenberg et al. We re-evaluate d the SAS energy for each united atom composing the solute. We took in to account the energy required to generate a void between adjacent sol ute molecules and the Coulombic interactions between atom-centered poi nt charges of solute molecules containing C, O, P, K+, Na+, and Cl- at oms in water. The modified SAS method well reproduced the various pmfs given by MD calculations or the integral equation method. The large a ctivation energy of K+-18-crown-6 complexation can be explained mostly by the void energy. The computational time required for the modified SAS method is approximately three to four orders of magnitude less tha n that by MD calculations. (C) 1997 John Wiley & Sons, Inc.