Ab initio quantum-chemical and kinetic studies of the O(¹D) + N₂(X₁Σ_g⁺) spin-forbidden quenching process

The spin-forbidden quenching reaction, O(¹D) + N₂(X¹Σ_g⁺) → N₂(X¹Σ_g⁺) + O(³P), has been studied by ab initio molecular orbital theory using different methods including CCSDTQ/CBS(TQ5)//CCSD(T)/aug-cc-pV5Z, whose energies were utilized for establishment of the singlet–triplet potential energy surface and prediction of thermal rate coefficients. The O(³P) + N₂ formation via the long-lived singlet ¹N₂O intermediate has been identified to be dominant for the spin-forbidden crossing at the crossing point located at 60.3 kcal mol⁻¹ above ¹N₂O, in good accordance with the literature values. The P,T-dependent rate constants predicted by the non-adiabatic RRKM theory agree closely with available results reported in the temperature range 50 – 700 K, over the pressure range of 1 – 250 Torr.