High-level ab initio predictions of CO2 center dot center dot center dot N2O structure

Ab initio calculations using MPn, QCISD, QCISD(T), and CCSD(T) methodologie s and cc-pVDZ, aug-cc-pVDZ, and cc-pVTZ correlation-consistrnt basis sets w ere carried out to determine the most stable structure of the CO2. . .N2O v an der Waals system. Rovibrational absorption and microwave spectroscopic c onstants are consistent with an approximately slipped parallel structure, b ut the experimental data cannot determine the orientation of N2O in the dim er. MPn and QCI methods lead to contradictory predictions. The QCI most sta ble structure, with the oxygen atom of N2O nearly over the carbon atom of C O2, is consistent with the experimental data. (C) 2001 John Wiley & Sons, I nc.