STUDY OF SOLVENT EFFECTS BY MEANS OF AVERAGED SOLVENT ELECTROSTATIC POTENTIALS OBTAINED FROM MOLECULAR-DYNAMICS DATA

We present the theory and implementation of a new approach for studyin g solvent effects. The electronic structure of the solute, calculated at the ab initio level, is obtained in the presence of the surrounding medium. We employ a mean field theory in which the solvent response i s described by means of point charges chosen in such a way that they r eproduce the average value of the solvent electrostatic potential calc ulated from molecular dynamics data. Ln this way, the complete solvent potential can be introduced into the solute Hamiltonian without makin g use of a one-center multiple expansion of the solute-solvent potenti al. Ln the proposed method, only one quantum calculation has to be per formed and a great number of configurations can easily be included mak ing the calculation statistically significant. We show that, despite t he large fluctuations in the solute charge distribution induced by the solvent, the proposed mean field theory adequately reproduces the ene rgetics and properties of formamide and water molecules in aqueous sol ution. (C) 1997 by John Wiley & Sons, Inc.