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Title: Quantum dynamics study on the CHIPR potential energy surface for the hydroperoxyl radical: The reactions O + OH⇋O{sub 2} + H

Abstract

Quantum scattering calculations of the O({sup 3}P)+OH({sup 2}Π)⇌O{sub 2}({sup 3}Σ{sub g}{sup −})+H({sup 2}S) reactions are presented using the combined-hyperbolic-inverse-power-representation potential energy surface [A. J. C. Varandas, J. Chem. Phys. 138, 134117 (2013)], which employs a realistic, ab initio-based, description of both the valence and long-range interactions. The calculations have been performed with the ABC time-independent quantum reactive scattering computer program based on hyperspherical coordinates. The reactivity of both arrangements has been investigated, with particular attention paid to the effects of vibrational excitation. By using the J-shifting approximation, rate constants are also reported for both the title reactions.

Authors:
;  [1]
  1. Departamento de Química and Centro de Química, Universidade de Coimbra, 3004-535 Coimbra (Portugal)
Publication Date:
OSTI Identifier:
22415461
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APPROXIMATIONS; CHEMICAL REACTION KINETICS; EXCITATION; HYDROGEN; HYDROPEROXY RADICALS; INTERACTION RANGE; OXYGEN; POTENTIAL ENERGY; REACTIVITY; SURFACES; VALENCE

Citation Formats

Teixidor, Marc Moix, and Varandas, António J. C., E-mail: varandas@uc.pt. Quantum dynamics study on the CHIPR potential energy surface for the hydroperoxyl radical: The reactions O + OH⇋O{sub 2} + H. United States: N. p., 2015. Web. doi:10.1063/1.4905292.
Teixidor, Marc Moix, & Varandas, António J. C., E-mail: varandas@uc.pt. Quantum dynamics study on the CHIPR potential energy surface for the hydroperoxyl radical: The reactions O + OH⇋O{sub 2} + H. United States. doi:10.1063/1.4905292.
Teixidor, Marc Moix, and Varandas, António J. C., E-mail: varandas@uc.pt. 2015. "Quantum dynamics study on the CHIPR potential energy surface for the hydroperoxyl radical: The reactions O + OH⇋O{sub 2} + H". United States. doi:10.1063/1.4905292.
@article{osti_22415461,
title = {Quantum dynamics study on the CHIPR potential energy surface for the hydroperoxyl radical: The reactions O + OH⇋O{sub 2} + H},
author = {Teixidor, Marc Moix and Varandas, António J. C., E-mail: varandas@uc.pt},
abstractNote = {Quantum scattering calculations of the O({sup 3}P)+OH({sup 2}Π)⇌O{sub 2}({sup 3}Σ{sub g}{sup −})+H({sup 2}S) reactions are presented using the combined-hyperbolic-inverse-power-representation potential energy surface [A. J. C. Varandas, J. Chem. Phys. 138, 134117 (2013)], which employs a realistic, ab initio-based, description of both the valence and long-range interactions. The calculations have been performed with the ABC time-independent quantum reactive scattering computer program based on hyperspherical coordinates. The reactivity of both arrangements has been investigated, with particular attention paid to the effects of vibrational excitation. By using the J-shifting approximation, rate constants are also reported for both the title reactions.},
doi = {10.1063/1.4905292},
journal = {Journal of Chemical Physics},
number = 1,
volume = 142,
place = {United States},
year = 2015,
month = 1
}
  • A switching function formalism is used to derive an analytic potential energy surface for the O + OH in equilibrium HO/sub 2/ in equilibrium H + O/sub 2/ reactive system. Both experimental and ab initio data are used to derive parameters for the potential energy surface. Trajectory calculations for highly excited HO/sub 2/ are performed on this surface. From these trajectories quasi-periodic eigentrajectories are found for vibrational levels near the HO/sub 2/ dissociation threshold with small amounts of quanta in the OH stretch mode and large amounts of quanta in the OO stretch mode.
  • The kinetics and dynamics of several O + O{sub 2} isotope exchange reactions have been investigated on a recently determined accurate global O{sub 3} potential energy surface using a time-dependent wave packet method. The agreement between calculated and measured rate coefficients is significantly improved over previous work. More importantly, the experimentally observed negative temperature dependence of the rate coefficients is for the first time rigorously reproduced theoretically. This negative temperature dependence can be attributed to the absence in the new potential energy surface of a submerged “reef” structure, which was present in all previous potential energy surfaces. In addition, contributionsmore » of rotational excited states of the diatomic reactant further accentuate the negative temperature dependence.« less
  • An eight dimensional time-dependent quantum dynamics wavepacket approach is performed for the study of the H₂+C₂H ! H + C₂H₂ reaction system on a new modified potential energy surface (PES) [Chem. Phys. Lett. 409, 249 (2005)]. This new potential energy surface is obtained by modifying Wang and Bowman's old PES [ J. Chem. Phys. 101, 8646 (1994)] based on the new ab initio calculation. This new modified PES has a much lower transition state barrier height at 2.29 kcal/mol than Wang and Bowman's old PES at 4.3 kcal/mol. This study shows the reactivity for this diatom-triatom reaction system is enchancedmore » by vibrational excitations of H₂; whereas, the vibrational excitations of C₂H only have a small effect on the reactivity. Furthermore, the bending excitations of C₂H, comparing to the ground state reaction probability, hinder the reactivity. The comparison of the rate constant between this calculation and experimental results agree with each other very well. This comparison indicates that the new modified PES corrects the large barrier height problem in Wang and Bowman's old PES.« less