Global fits of new intermolecular ground state potential energy surfaces for N2–H2 and N2–N2 van der Waals dimers

We have built new global fits for the ground state potential energy surfaces (PES) of N2–H2 and N2–N2 complexes using ab initio perturbative and supermolecular methods. The analytical expressions used in the four-dimensional fitting procedure require the knowledge of the multipole moments, the static and dynamic multipolar polarizabilities of each monomer, from which long-range electrostatic, induction and dispersion coefficients are evaluated. In agreement with previous work, we have found the most stable conformation of N2–H2 to be linear and that of N2–N2 to have a 45/50° canted parallel shape. The quality of present PESs have been checked by comparing between calculated and experimental second virial coefficients and integral scattering cross-sections, which are found to be in good agreement.