The C(3P) + NO(X2Π) → O(3P) + CN(X2Σ+), N(2D)/N(4S) + CO(X1Σ+) reaction: Rates, branching ratios, and final states from 15 K to 20 000 K

Abstract

The C + NO collision system is of interest in the area of high-temperature combustion and atmospheric chemistry. In this work, full dimensional potential energy surfaces for the A',A″, and A″ electronic states of the [CNO] system have been constructed following a reproducing kernel Hilbert space approach. For this purpose, more than 50 000 energies are calculated at the MRCI+Q/aug-cc-pVTZ level of theory. The dynamical simulations for the C(P) + NO(XΠ) → O(P) + CN(XΣ), N(D)/N(S) + CO(XΣ) reactive collisions are carried out on the newly generated surfaces using the quasiclassical trajectory (QCT) calculation method to obtain reaction probabilities, rate coefficients, and the distribution of product states. Preliminary quantum calculations are also carried out on the surfaces to obtain the reaction probabilities and compared with QCT results. The effect of nonadiabatic transitions on the dynamics for this title reaction is explored within the Landau-Zener framework. QCT simulations have been performed to simulate molecular beam experiment for the title reaction at 0.06 and 0.23 eV of relative collision energies. Results obtained from theoretical calculations are in good agreement with the available experimental as well as theoretical data reported in the literature. Finally, the reaction is studied at temperatures that are not practically achievable in the laboratory environment to provide insight into the reaction dynamics at temperatures relevant to hypersonic flight.

High-dimensional potential energy surfaces for molecular simulations: from empiricism to machine learning

“…This yields, for example, an RMSD of 0.99 kcal mol −1 for 3701 fitted points from electronic structure calculations at the multi reference configuration interaction (MRCI) level of theory for CNO [42]. As a comparison, another recent investigation of the same system [43] using a reproducing kernel Hilbert space (RKHS, see further below) representation yielded an RMSD of 0.38, 0.48 and 0.47 kcal mol −1 for the 2 A′, 2 A″ and 4 A″ electronic states using more than 10 000 ab initio points for each surface.…”

“…One example for such a system constitutes the reactive dynamics of [CNO] in the hypersonic regime at temperatures up to T = 20 000 K [43]. The C+NO reaction is important in combustion chemistry and NO plays a crucial role in the chemistry near the surface of a space vehicle during atmospheric reentry [105].…”

“…Until now, computational studies of Diels-Alder reactions including the molecular dynamics have ) reaction compared with available computed [114] and experimental [106,107,[115][116][117] results reported in the literature are also shown. Results from simulations without and with nonadiabatic transitions treated at the trajectory surface hopping (TSH) level are compared [43]. Figure adapted from [43].…”

“…Results from simulations without and with nonadiabatic transitions treated at the trajectory surface hopping (TSH) level are compared [43]. Figure adapted from [43].…”

“…The diatoms are fixed at their equilibrium geometry and the zero of energy is set to the asymptotic value for each channel. Data taken form[43].…”