Quantum calculations of the O(3P)+H2→OH+H reaction

Abstract

Quantum scattering calculations are reported for the O(3P)+H2(v=0,1) reaction using chemically accurate potential energy surfaces of 3A' and 3A" symmetry. We present state-to-state reaction cross sections and rate coefficients as well as thermal rate coefficients for the title reaction using accurate quantum calculations. Our calculations yield reaction cross sections that are in quantitative accord with results of recent crossed molecular beam experiments. Comparisons with results obtained using the J-shifting calculations show that the J-shifting approximation is quite reliable for this system. Thermal rate coefficients from the exact calculations and the J-shifting approximation agree remarkably well with experimental results. Our calculations also reproduce the markedly different OH(v'=0)/OH(v'=1) branching in O(3P)+H2(v=1) reaction, observed in experiments that use different O(3P) atom sources. In particular, we show that the branching ratio is a strong function of the kinetic energy of the O(3P) atom.

State-to-State Quantum Dynamics of Reactions O(3P) + HD (v = 0–1, j = 0) → OH+D and OD+H: Reaction Mechanism and Vibrational Excitation

“…The above argument is further supported by the fact that the ICSs obtained from recent crossed molecular beam measurements 11 are in a good agreement with the calculation results on the singlet PES 3 A′ and 3 A″. 24 Thus, for the sake of simplicity, we carried out the state-to-state dynamics calculations of the title reactions on the single-surface 3 A″ of Rogers et al 6 As indicated in ref 6, 951 geometries were used to the regular-accuracy MOLPRO calculations of the electronic energies for the lowest 3 A″ state of the title reactions. A rotating Morse spline method and a generalized London− Eyring−Polanyi−Sato (LEPS) double-polynomial method were employed to fit the results.…”

A quantum wave-packet study of intersystem crossing effects in the O(P2,1,3,D21)+H2 reaction

“…We should mention here that Braunstein et al 20 and Balakrishnan 21 have reported their nonadiabatic dynamics calculations on the O͑ 3 P͒ +H 2 reaction very recently, and the agreement between these calculated total reaction cross sections and the experimental results tends to indicate the insignificance of the spin-orbit effects in this reaction. However, the present study differs apparently from the above investigations partly in that the problem of interest is not the spinorbit effects on the total reaction cross sections but on the fine-structure resolved reaction cross sections.…”

Dynamics of the O(P3)+H2 reaction at low temperatures: Comparison of quasiclassical trajectory with quantum scattering calculations

“…18 Owing to this experimental breakthrough and the availability of new ab initio PESs of chemical accuracy, 16,22 there currently is a renewed theoretical interest in the title reaction. 3,[18][19][20][21][22][23] Recently, Braunstein et al 20 reported the excitation function for O͑ 3 P͒ +H 2 ͑v =0−3, j =0͒ → OH+ H calculated with the quasiclassical trajectory ͑QCT͒ and time-dependent quantum-mechanical ͑TDQM͒ scattering methods on the PESs of Rogers et al 16 QCT reaction cross sections for H 2 ͑v Ͼ 0͒ were found to overestimate TDQM results by as much as a factor of Ϸ2 near threshold, although the agreement is gradually restored as the collision energy is increased. Using the same PESs, time-independent coupled-channel quantum scattering calculations by Balakrishnan 21 obtained cross sections in close agreement with the experiment and TDQM results.…”