Quantum chemical fully ab initio conformational calculations was performed
for the weakly bound van der Waals N-2...H2 and N-2...He dimers in the fram
ework of the supermolecule approach. The counterpoise-corrected interaction
energies were computed through fourth order MBPT using basis sets construc
ted to give accurate values for the electric moments, polarizabilities and
dispersion energy contributions. The best size-to-performance ratio basis s
et found in the present study, predicts the T-shaped structure to be the mo
st stable configuration for N-2...He, with a well depth D-e of 2.68 meV at
a minimum distance R-e of 3.44 Angstrom, in close agreement with calculatio
ns performed with larger basis sets. The relative stability of the configur
ations studied for N-2...H-2 were: collinear structure > parallel structure
> T-shaped structures. The collinear structure represent the most stable c
onfiguration, with a D-e value of 8.35 meV at a equilibrium distance R-e of
7.60a(0). (C) 1999 Elsevier Science B.V. All rights reserved.