^{1}, Changjian Xie

^{2}, Daiqian Xie

^{2,a)}and Hua Guo

^{1,a)}

### Abstract

The adiabatic state-to-state dynamics of the reaction between O(^{3} *P*) and NH(*X* ^{3}Σ^{−}) has been investigated on three lowest-lying electronic states, namely, the *X* ^{1} *A* ^{′}, *A* ^{1} *A* ^{″}, and *a* ^{3} *A* ^{″} states, using the recently developed global potential energy surfaces based on high level * ab initio * data. The reaction rate has contributions from all three states, with the largest coming from the triplet state. The rotational and vibrational degrees of freedom of the prominent NO product are highly excited, although significant differences exist in the internal state distributions of the three adiabatic channels. The reaction proceeds with a complex-forming mechanism on all three electronic states, as evidenced by resonance structures in reaction probabilities and the near forward-backward symmetry in the differential cross section. However, significant non-reactive scattering and inverted vibrational state distributions suggest substantial non-statistical behaviors.

This work was supported by the Department of Energy (DOE) (DE-FG02–05ER15694 to H.G.), the National Natural Science Foundation of China (NNSFC) (Grant Nos. 21133006 and 21273104 to D.X.) and the Chinese Ministry of Science and Technology (Grant No. 2013CB834601 to D.X.). We also thank Professor Zhigang Sun for numerous discussions on the quantum scattering theory. The computation was performed at NERSC and the IBM Blade cluster system in the High Performance Computing Center of Nanjing University.

I. INTRODUCTION

II. POTENTIAL ENERGY SURFACES

III. QUANTUM DYNAMICS

IV. RESULTS AND DISCUSSION

A. Potential energy surfaces

B. Numerics of dynamical calculations

C. Reaction probabilities

D. Integral cross sections and rate constants

E. Vibrational state distributions

F. Rotational state distributions

G. Differential cross sections

V. CONCLUSIONS

### Key Topics

- Reaction rate constants
- 20.0
- Non adiabatic reactions
- 18.0
- Hydrogen reactions
- 12.0
- Chemical reaction cross sections
- 11.0
- Vibrational states
- 8.0

## Figures

Schematic energy level diagram of HNO/HON for three lowest-lying states: *X* ^{1} *A* ^{′} (blue dash curve), *a* ^{3} *A* ^{″} (red solid curve), and *A* ^{1} *A* ^{″} (green dotted curve). The *ab initio* energies of the stationary points are given in eV relative to the H + NO dissociation limit.

Schematic energy level diagram of HNO/HON for three lowest-lying states: *X* ^{1} *A* ^{′} (blue dash curve), *a* ^{3} *A* ^{″} (red solid curve), and *A* ^{1} *A* ^{″} (green dotted curve). The *ab initio* energies of the stationary points are given in eV relative to the H + NO dissociation limit.

Contours of the three PESs in the H + NO product Jacobi coordinates (*R* ^{′}, *r* ^{′}, γ^{′}) with optimized O–N distance *r* ^{′}. The stationary points are shown by yellow dots. The contours are spaced by 0.3 eV relative to the H + NO dissociation limit.

Contours of the three PESs in the H + NO product Jacobi coordinates (*R* ^{′}, *r* ^{′}, γ^{′}) with optimized O–N distance *r* ^{′}. The stationary points are shown by yellow dots. The contours are spaced by 0.3 eV relative to the H + NO dissociation limit.

Total reaction probabilities as a function of the collision energy for the O + NH reaction at several *J* values.

Total reaction probabilities as a function of the collision energy for the O + NH reaction at several *J* values.

Energy dependence of the calculated total ICS for the O + NH(*v* _{ i } = 0, *j* _{ i } = 0) → H + NO reaction (upper panel) and comparison between calculated and experimental rate constants (filled triangle is from Ref. ^{ 13 } and filled circle is from Ref. ^{ 16 } ) as a function of temperature (lower panel).

Energy dependence of the calculated total ICS for the O + NH(*v* _{ i } = 0, *j* _{ i } = 0) → H + NO reaction (upper panel) and comparison between calculated and experimental rate constants (filled triangle is from Ref. ^{ 13 } and filled circle is from Ref. ^{ 16 } ) as a function of temperature (lower panel).

Product vibrational state distributions for both (R2) and (R2PRIME) at three collision energies.

Product vibrational state distributions for both (R2) and (R2PRIME) at three collision energies.

Comparison of the QM product vibrational state distributions with experimental and previous QCT results for the O + NH (*v* _{ i } = 0, *j* _{ i } = 0) → H + NO reaction at *E* _{ c } = 0.1 eV. All distributions are normalized.

Comparison of the QM product vibrational state distributions with experimental and previous QCT results for the O + NH (*v* _{ i } = 0, *j* _{ i } = 0) → H + NO reaction at *E* _{ c } = 0.1 eV. All distributions are normalized.

Product rotational state distributions for the O + NH (*v* _{ i } = 0, *j* _{ i } = 0) → H + NO reaction on all three PESs at *E* _{ c } = 0.1 eV.

Product rotational state distributions for the O + NH (*v* _{ i } = 0, *j* _{ i } = 0) → H + NO reaction on all three PESs at *E* _{ c } = 0.1 eV.

Total DCSs for both (R2) and (R2PRIME) at three collision energies.

## Tables

Relative energies (in eV) of the stationary points located on the PESs of three electronic states.

Relative energies (in eV) of the stationary points located on the PESs of three electronic states.

Numerical parameters used in the quantum mechanical wave packet calculations. (Atomic units are used unless stated otherwise.)

Numerical parameters used in the quantum mechanical wave packet calculations. (Atomic units are used unless stated otherwise.)

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