Solvation of Sodium Chloride: An Effective Fragment Study of NaCl(H2O)n

Calculations on NaCl microsolvated with up to 10 water molecules were performed by treating the NaCl with restricted Hartree−Fock (RHF) 6-31G(d) ab initio wave functions and the waters with the effective fragment potential (EFP) model. Increasing numbers of local minima are found with the addition of successive water molecules. As the number of waters is increased, the Boltzmann-averaged NaCl bond distance lengthens from 2.397 to 3.167 Å, the Mulliken charges increase to ±0.98, and the Boltzmann-averaged NaCl stretching frequency decreases from 359 to 94 cm-1. The incremental binding energies (in kcal/mol) as a function of n are 15.4 (n = 1), 15.1 (n = 2), 14.0 (n = 3), 13.9 (n = 4), 12.3 (n = 6), 12.8 (n = 8), 9.1 (n = 10). Disciplines Chemistry Comments Reprinted (adapted) with permission from Journal of Physical Chemsitry A 103 (1999): 4162, doi:10.1021/ jp984806l. Copyright 1999 American Chemical Society. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/chem_pubs/347 Solvation of Sodium Chloride: An Effective Fragment Study of NaCl(H2O)n Christian P. Petersen and Mark S. Gordon* Department of Chemistry, Iowa State UniVersity, Ames, Iowa 50011 ReceiVed: December 29, 1998; In Final Form: March 3, 1999 Calculations on NaCl microsolvated with up to 10 water molecules were performed by treating the NaCl with restricted Hartree-Fock (RHF) 6-31G(d) ab initio wave functions and the waters with the effective fragment potential (EFP) model. Increasing numbers of local minima are found with the addition of successive water molecules. As the number of waters is increased, the Boltzmann-averaged NaCl bond distance lengthens from 2.397 to 3.167 Å, the Mulliken charges increase to (0.98, and the Boltzmann-averaged NaCl stretching frequency decreases from 359 to 94 cm-1. The incremental binding energies (in kcal/mol) as a function of n are 15.4 (n ) 1), 15.1 (n ) 2), 14.0 (n ) 3), 13.9 (n ) 4), 12.3 (n ) 6), 12.8 (n ) 8), 9.1 (n ) 10).