Proton transfer between water molecules: a theoretical study of solvent effects using the continuum and the discrete-continuum models

Abstract

Proton transfer between two water molecules both in the gas phase and in solution has been studied at the HF/6-311G ** level. For the gas phase we have characterized the reduced potential energy surface. Proton transfer in solution has been modeled with a pure continuum model and with a mixed discrete-continuum model where the two water molecules between which the proton is transferred are surrounded with four more water molecules and a continuum. Both in the gas phase and in solution the proton transfer between the two water molecules presents a double-well potential with a barrier of 0.30 kcal/mol in the gas phase and, in solution, 1.54 kcal/mol in the continuum model and 0.99 kcal/mol in the mixed discrete-continuum model