Multitemperature Dissociation Rate of N2 + N2 → N2 + N + N Calculated Using Selective Sampling Quasi-Classical Trajectory Analysis

The dissociation rate of nitrogen for the reaction N-2 + N-2 -> N-2 + N + N was calculated as a function of a translational, vibrational, and rotational temperature, each ranging from 6000 to 60,000K. The rate coefficients were calculated using quasi-classical trajectory analysis, in which approximately 5.35 billion trajectories were directly simulated. Furthermore, a new selective sampling procedure was implemented so that only trajectories with sufficient energy to cause dissociation were sampled. At 6000K, this method reduced the computational cost by nearly two orders of magnitude. Finally, the set of rate coefficients was used to extend the two-temperature model conventionally used in computational-fluid-dynamics simulations. For temperatures between 13,000 and 40,000K, where rotational energy of N-2 should be independently modeled, the fit shows good agreement with the quasi-classical trajectory-calculated rate coefficients.