Long-range interaction for dimers of atmospheric interest: dispersion, induction and electrostatic contributions for O(2)-O(2), N(2)-N(2) and O(2)-N(2).

Electric multipole moments, static dipole polarizabilities, and dynamic dipole, quadrupole, and mixed dipole-octupole polarizabilities of molecular oxygen and nitrogen in their ground electronic states have been obtained by means of high level multiconfigurational ab initio calculations. From these properties, we have obtained electrostatic, dispersion, and induction coefficients for the long-range interactions of the O(2)-O(2) , N(2)-N(2) , and O(2)-N(2) dimers. Our data is a comprehensive and consistent set that for N(2)-N(2) shows a very good agreement with previous accurate calculations, whereas for quantities involving open-shell O(2) represents a considerable improvement over previous estimations. Moreover, the long-range interaction is analyzed and compared for the different interacting partners. It is found that the C(8) dispersion interaction plays a nonnegligible role and that the induction component is only important for a detailed description of the highest order anisotropy terms in the spherical harmonics expansion of the long-range potential. It is also found that the total long-range interaction is quite similar in O(2)-O(2) and O(2)-N(2) , and that differences with N(2)-N(2) are mainly because of the important role of the electrostatic interaction in that dimer. Comparison with high level supermolecular calculations indicates that the present long-range potentials are accurate for intermolecular distances larger than about 15 bohr.