The aqueous solvation of sodium chloride:: A Monte Carlo transition path sampling study

We study the dissociation of sodium chloride in an environment of simple point charged model waters using a stochastic transition path sampling method. The method is able to analyze the structure and dynamics (including transition states) of rare events without any a priori assumption. After an ensemble of reactive paths between stable states has been constructed, a set of transition state configurations can be derived. Technical details of the simulation are discussed. We observe that the structure found from the ensemble of transition state configurations is qualitatively equal to the structure obtained when the interionic distance is assumed as the reaction coordinate. We also discuss energetic aspects of the ion pair dissociation: A free energy profile of the dynamical process reveals the contribution of solvent degrees of freedom to the reaction barrier. (C) 2000 American Institute of Physics. [S0021-9606(00)50326-2].