Monte Carlo calculations of solvent effect in the reaction F- + CH3F = F...CH3....F-

Abstract

A new approach is suggested and tested to calculation of solvent effect on chemical reactivity based on the statistical-thermodynamic Monte Carlo simulation of models of aqueous solutions devised by Metropolis. The results of computer experiments are presented for the following systems: F-.26H2O, CH3F.26H2O, FCH3F-.52H2O, 26 H2O, 52 H2O at a temperature of 300 K at the conditions of canonical ensemble. The pair potentials MCY-CI (for water-water interactions) and 4-31G (for solute-water interactions) have been used. The 4-31G potentials have been derived from the SCF calculations of the interaction energies of the systems: F-.H2O, CH3F.H2O, and FCH3F-.H2O. Internal energies, radial distribution functions, and snapshots of the configurations have been calculated. The calculated partial molar internal energies depend strongly on quality of the solute-water pair potentials and are overestimated with respect to experiment. On the basis of the results obtained, further possibilities of the suggested approach are discussed.