Study of the structure of molecular complexes. V. Heat of formation for the Liplus;, Naplus;, Kplus;, Fminus;, and Clminus;ion complexes with a single water molecule

摘要

In order to obtain the heat of formation Dgr;H, for the ionhyphen;water complexes previously studied in the Hartreehyphen;Fock approximation in the first three papers of this series, we have computed the normal frequencies of the complexes, the zerohyphen;point energy correction to Dgr;H, and themolecular extra correlation energy. The main contribution to Dgr;His due to the Hartreehyphen;Fock binding; the least important contribution results from the correlation effects. The Hartreehyphen;Fock binding varies from about 35 kcalsol;mole (Liplus;sngbnd;H2O) to about 12 kcalsol;mole (Clminus;sngbnd;H2O); the zerohyphen;point correction is between 1 and 2 kcalsol;mole; and the molecular extra correlation correction is less than 1 kcalsol;mole. The computation of Dgr;His analyzed in order to estimate upper and lower bounds. We conclude that the calculated Dgr;Hvalues are accurate to about 2.0 kcalsol;mole. Experimental data support this conclusion. In the Appendix, the potentials for waterhyphen;ion complexes have been presented in the form of a simple analytical expansion. The expansion has been obtained by fitting the Hartreehyphen;Fock computed energies for the waterhyphen;ion complexes.