COMPUTATIONAL STUDIES OF ATMOSPHERIC CHEMISTRY SPECIES .11. A COMPUTATIONAL STUDY OF 2 AR-N2 COMPLEXES

Harmonic vibrations in the Ar-N2 complexes are computed ab initio usin g the second-order Moller-Plesset (MP2) perturbation treatment with th e 6-31G basis set; the energetics are refined at the fourth-order Moll er-Plesset (MP4) level. Two different minimum energy structures are fo und-T-shaped and linear- the latter being lower in energy. The inter-s ystem vibrations exhibit 30 cm-1 or lower frequencies. The intramolecu lar N2 frequency is lowered by about 0.4 cm-1 comparing to a free N2 m olecule. The highest IR intensity is found for the intramolecular mode in the T-shaped structure. The results are relevant for planetary-atm osphere spectroscopy.