Reactive collisions for NO(2Π) + N(4S) at temperatures relevant to the hypersonic flight regime

Abstract

The NO(X²Π) + N(⁴S) reaction which occurs entirely in the triplet manifold of N₂O is investigated using quasiclassical trajectories and quantum simulations. Fully-dimensional potential energy surfaces for the ³A′ and ³A′′ states are computed at the MRCI+Q level of theory and are represented using a reproducing kernel Hilbert space. The N-exchange and N₂-formation channels are followed by using the multi-state adiabatic reactive molecular dynamics method. Up to 5000 K these reactions occur predominantly on the N₂O ³A′′ surface. However, for higher temperatures the contributions of the ³A′ and ³A′′ states are comparable and the final state distributions are far from thermal equilibrium. From the trajectory simulations a new set of thermal rate coefficients of up to 20 000 K is determined. Comparison of the quasiclassical trajectory and quantum simulations shows that a classical description is a good approximation as determined from the final state analysis.