State-to-State Oxygen and Nitrogen Recombination Rates Computed Using Selectively Sampled Quasiclassical Trajectories

Gas-phase recombination is observed in several hypersonic flow environments involving rapid cooling and acceleration through expansion. However, high-fidelity kinetic databases for these conditions are often unavailable due to the difficulty in resolving reaction rate coefficients using Monte Carlo methods at relatively low temperatures. In this work, we demonstrate the application of a selective sampling methodology to calculate highly accurate rovibrational state-specific dissociation rate coefficients between temperatures 1000 and 5000 K and the calculation of recombination rate coefficients using microscopic reversibility. Selective sampling results in statistically better resolved dissociation rate coefficients at much lower computational costs. The calculated rate coefficients for the [Formula: see text] and [Formula: see text] systems exhibit excellent agreement with literature over a wide range of temperatures and comprise two of the few high-fidelity databases that contain rate coefficients at temperatures of below 2500 K. Isothermal heat bath simulations are used to verify the accuracy of the databases obtained using selective sampling. The existing and updated [Formula: see text] kinetic databases are in excellent agreement in terms of both macroscopic and microscopic parameters, while differences arise between the [Formula: see text] databases due to the comparatively lower resolution of the existing [Formula: see text] database. The updated kinetic databases are available upon request.