Exchange-Coulomb potential energy surfaces, and related physical properties, for KrN2 Original Research Article

The construction of exchange-Coulomb (XC) potential energy models for closed shell atom-closed shell molecule interactions, based on earlier work for rare gas-rare gas interactions, is discussed with explicit application to the KrN2 interaction. The construction of the new XC potential energy surface for KrN2 is based on recent results for the Heitler-London interaction energy, the long range dispersion energies, and the microwave spectra for this dimer. The adjustable parameters in the final XC potential are determined by fitting experimental second virial coefficients (all within experimental error), as a function of temperature, and three lines of the microwave spectra. With no further adjustment of parameters the resulting potential yields excellent predictions for all the frequencies of all the microwave transitions studied experimentally for seven isotopomers of KrN2, and good agreement with experiment for the binary diffusion, the interaction viscosity, and the mixture viscosity coefficients of KrN2 and for the cross sections associated with depolarized light scattering and nuclear spin relaxation for the KrN2 system. The agreement with experiment for the latter five properties is as good as can be expected from our scaled Mason-Monchick/infinite order sudden calculations for these properties. The final XC2 potential is apparently the most reliable potential to date for the KrN2 interaction and provides a very suitable starting point for further studies of the KrN2 system; the flexibility still inherent in the potential can be used, as required, for this purpose.