Mechanistic insight into the N2O + O(1D,3P) reaction: role of post-CCSD(T) corrections and non-adiabatic effects

In the present work, we have studied the N2O + O(D-1,P-3) reaction using high level quantum chemical calculations along with non-adiabatic kinetics. For quantum chemical calculations, we used the postCCSD(T) method, which includes corrections from full triple excitations and partial quadratic excitations at the coupled-cluster level. For both the paths (N-2 + O-2 and 2NO), we have computed the rate constants over a wide range of temperatures (100-500 K for singlet paths and 700-4000 K for triplet paths). To assess the accuracy of our computations, we have compared our results with various experimentally measured quantities (absolute rate constant, branching fraction, and crossover temperature) and found a good match with all of them. We recommend the Arrhenius expressions for singlet paths, which turn out to be 4.46 x 10(-11)exp(0.022/R7) cm(3) molecule(-1) s(-1) and 7.12 x 10(-11)exp(0.024/R7) cm(3) molecule(-1) s(-1)for N-2 + O(2 )and NO paths, respectively. For triplet paths, our recommended Arrhenius expressions are 5.15 x 10(-12) exp(-15.35/R7) cm(3) molecule(-1) s(-1) and 1.59 x 10(-10 )exp(-27.76/ RT) cm(3 )molecule(-1) s(-1)for N-2 + O-2 and NO paths, respectively.