CALCULATION OF SOLVATION ENERGIES - THE SELF-CONSISTENT MULTIPOLE MOMENT REACTION FIELD METHOD

The self-consistent multipole moment reaction field (SCMMRF) method is proposed as a simple alternative to the conventional self-consistent reaction field (SCRF) technique for the calculation of solvation energ ies within the confines of the dielectric continuum model. The SCMMRF method represents a straightforward generalization of the original Kir kwood method by the inclusion of the solute's polarizability. Formally , the SCMMRF method is identical to SCRF through second order in the r eaction held in its present formulation, i.e., hyperpolarizability con tributions are neglected. The SCMMRF method is particularly cost-effec tive when applied in conjunction with correlated wavefunctions, since it requires only multipole moments and their polarizabilities to be co mputed. Test calculations for the water and pyrimidine molecules and f or several H2O clusters demonstrate that the SCMMRF technique is a num erically reliable alternative to SCRF. Using a composite discrete-cont inuum approach, the hydration energy of water has been computed to be -8.9 kcal mol(-1), in acceptable agreement with the experimental value of -9.7 kcal mol(-1).