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 N-2-H-2, and N-2-N-2 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 N-2-H-2 to be linear and that of N-2-N-2 to have a 45/50 degrees 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. (C) 2007 Elsevier B.V. All rights reserved.