Solvation effect on the lnteraction between sodium and chloride lons in aqueous solution: An analysis based on the new resonance theory

The solvation effect on the nature of the interaction between sodium and chloride ions in aqueous solution is investigated theoretically by using the combination of RISM-SCF method and the analysis of molecular orbital wave function based on the new resonance theory. This strategy offers unified understandings of the nature of the interatomic interaction in solution together with the statistical distribution of solvent water molecules. The results show that, in aqueous phase, the weight of covalent interaction decrease rapidly with increase the distance between sodium and chloride and, at the same time, coordination number of solvent increase. We also find the solvation effect enhances the ionic character of the interaction by up to 20%. (C) 2007 Wiley Periodicals, Inc.