Reaction dynamics for the [NNO] system from state-resolved and coarse-grained models

Abstract

The dynamics for the NO(X2Π) + N(4S) ↔ N2(X1Σg+) + O(3P) reaction was followed in the 3A′ electronic state using state-to-state (STS) and Arrhenius-based rates from two different high-level potential energy surfaces represented as a reproducing kernel Hilbert space (RKHS, PESB for “Basel PES”) and permutationally invariant polynomials (PIPs, PESM for “Minnesota PES”). Despite the different number of bound states supported by PESB and PESM, the ignition points from STS and Arrhenius rates are at ∼10−6 s whether or not reverse rates are from assuming microreversibility or explicitly given. Conversion from NO to N2 is incomplete if Arrhenius rates are used, but complete turnover is observed if STS information is used. This is due to non-equilibrium energy flow and state dynamics, which requires a state-based description. Including full dissociation asymptotically leads to the correct 2:1 [N]:[O] concentration with little differences for the species’ dynamics depending on the PES used for the STS information. In conclusion, concentration profiles from coarse-grained simulations are consistent over 14 orders of magnitude in time using STS information based on two different high-level PESs.