POSSIBLE IMPROVEMENTS OF THE INTERACTION ENERGY CALCULATED USING MINIMAL BASIS SETS

Interaction energies for H2O·H2O, H2O·F- and H2O·CH4 have been calculated using the LCAO MO SCF method with minimal basis sets, and employing the counterpoise method to eliminate the basis set superposition error. The results compare favourably with those obtained using extended basis sets. It is shown that for H2O·H2O and for the benzene-carbonyl cyanide complex a large part of the dispersion energy can easily be obtained as a sum of bond-bond dispersion energies calculated from a London-type formula using experimental values of the bond polarizability tensors. By considering the interaction between a water and a glycine molecule it is also shown that the dispersion energy plays an important role in the hydration of organic molecules. © 1979 Springer-Verlag.