Theoretical studies of vibrational excitation in collisions of O(3<i>P</i>) with H2O(1<i>A</i>1)

Redmon, Michael J.; Schatz, George C.; Garrett, Bruce C.

doi:10.1063/1.450574

Cited by 21 publications

(16 citation statements)

References 29 publications

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“…7, the purple line with symbols represents tabulated results, and the purple line with no symbols shows results obtained by fitting to a functional form as shown in Figures 1 and 2 of Ref. 7. The quoted statistical error is about 5%-10% for the fundamental bend mode and about 20%-25% for the fundamental stretch modes.…”

Section: Qct Results Using the Brsg Surfacementioning

confidence: 90%

“…In principle, the present QCT ACT results with ZP0 (conventional histogram binning) use the same methods as Redmon et al 7 and the results should be directly comparable. The present results for ZP0 only match the results of Redmon et al 7 at 8 km s −1 .…”

Section: Qct Results Using the Brsg Surfacementioning

confidence: 95%

“…The authors of the BRSG surface note that it is best suited to collision energies up to 3.0 eV (69.2 kcal mol −1 ). 7 As discussed in Sec. I, the BRSG surface was previously used for quasi-classical trajectory calculations 8 and quantum scattering calculations.…”

Section: A Potential Surfacesmentioning

confidence: 97%

“…One was the non-reactive O( 3 P) + H 2 O( 1 A 1 ) surface developed by Bartlett, Redmon, Schatz, and Garrett (BRSG). 7,8,19 This surface is a Sorbie-Murrell many-body fit of ab initio MBPT calculations, 24 including an analytical fit to the non-bonding, pairwise and three body interactions between O and each atom in the H 2 O molecule as well as an analytical fit to the ab initio surface of H 2 O. The authors of the BRSG surface note that it is best suited to collision energies up to 3.0 eV (69.2 kcal mol −1 ).…”

Section: A Potential Surfacesmentioning

confidence: 99%

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Classical dynamics of state-resolved hyperthermal O(3P) + H2O(1A1) collisions

Braunstein

Conforti²

2013

The Journal of Chemical Physics

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Classical dynamics calculations are performed for O((3)P) + H2O((1)A1) collisions from 2 to 10 km s(-1) (4.1-101.3 kcal mol(-1)), focusing on product internal energies. Several methods are used to produce ro-vibrationally state-resolved product cross sections and to enforce zero-point maintenance from analysis of the classical trajectories. Two potential energy surfaces are used: (1) a recently developed set of global reactive surfaces for the three lowest triplet states which model OH formation, H elimination to make H + OOH, O-atom exchange, and collisional excitation and (2) a non-reactive surface used in past classical and quantum collision studies. Comparisons to these previous studies suggest that for H2O vibrational excitation, classical dynamics which include gaussian binning procedures and/or selected zero-point maintenance algorithms can produce results which approximate quantum scattering cross sections fairly well. Without these procedures, the classical cross sections can be many orders of magnitude greater than the quantum cross sections for exciting the bending vibration of H2O, especially near threshold. The classical cross section over-estimate is due to energy borrowing from stretching modes which dip below zero-point values. For results on the reactive surfaces, the present calculations show that at higher velocities there is an unusually large amount of product internal excitation. For OOH, where 40% of available collision energy goes into internal motion, the excited product vibrational and rotational energy distributions are relatively flat and values of the OOH rotational angular momentum exceed J = 100. Other product channel distributions show an exponential fall-off with energy consistent with an energy gap law. The present detailed distributions and cross sections can serve as a guide for future hyperthermal measurements of this system.

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Section: Qct Results Using the Brsg Surfacementioning

confidence: 90%

Section: Qct Results Using the Brsg Surfacementioning

confidence: 95%

Section: A Potential Surfacesmentioning

confidence: 97%

Section: A Potential Surfacesmentioning

confidence: 99%

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Classical dynamics of state-resolved hyperthermal O(3P) + H2O(1A1) collisions

Braunstein

Conforti²

2013

The Journal of Chemical Physics

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“…[13][14][15][16] Although these studies have had some success in explaining measurements in the 1-5 µ region, there remain major differences between these studies and measurements at certain collision velocities and significant differences between the theoretical results themselves.…”

Section: π)mentioning

confidence: 99%

Potential Surfaces and Dynamics of the O(3P) + H2O(X1A1) yields OH(X2Pi) + OH(X2Pi) Reaction

Braunstein¹,

Panfili²,

Shroll³

et al. 2004

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We present global potential energy surfaces for the three lowest triplet states in O( 3 P Π) reaction using these surfaces. The surfaces are spline-based fits of ~20,000 fixed geometry ab-initio calculations at the CASSCF+MP2 level with a O(4s3p2d1f)/H(3s2p) one electron basis set. Computed rate constants compare well to measurements in the 1,000-2,500 K range using these surfaces. We also compute the total, rovibrationally resolved, and differential angular cross sections at fixed collision velocities from near threshold at ~4 km s -1 (16.9 kcal mol -1 collision energy) to 11 km s -1 (122.5 kcal mol -1 collision energy), and we compare these computed cross sections to available space-based and laboratory data. A major finding of the present work is that above ~40 kcal mol -1 collision energy ro-vibrationally excited OH(X 2 Π) products are a significant and perhaps dominant contributor to the observed 1-5 µ spectral emission from O( 3 P) + H 2 O(X 1 A 1 ) collisions. Another important result is that OH(X 2 Π) products are formed in two distinct ro-vibrational distributions.)The 'active' OH products are formed with the reagent O-atom, and their ro-vibrational distributions are extremely hot. The remaining 'spectator' OH is relatively ro-vibrationally cold.For the active OH, rotational energy is dominant at all collision velocities, but the opposite holds for the spectator OH. Summed over both OH products, below ~50 kcal mol -1 collision energy, vibration dominates the OH internal energy, and above ~50 kcal mol -1 rotation is greater than vibrational energy. As the collision energy increases, energy is diverted from vibration to mostly translational energy. We note that the present fitted surfaces can also be used to investigate direct We present global potential energy surfaces for the three lowest triplet states in O(3P) + H2O(X1A1) collisions and present results of classical dynamics calculations on the O(3P) + H2O(X1A1) OH(X2) + OH(X2) reaction using these surfaces. The surfaces are spline-based fits of 20,000 fixed geometry ab-initio calculations at the CASSCF+MP2 level with a O(4s3p2d1f)/H(3s2p) one electron basis set. Computed rate constants compare well to measurements in the 1,000-2,500 K range using these surfaces. We also compute the total, ro-vibrationally resolved, and differential angular cross sections at fixed collision velocities from near threshold at ~4 km s-1 (16.9 kcal mol-1 collision energy) to 11 km s-1 (122.5 kcal mol-1 collision energy), and we compare these computed cross sections to available space-based and laboratory data. A major finding of the present work is that above ~40 kcal mol-1 collision energy ro-vibrationally excited OH(X2) products are a significant and perhaps dominant contributor to the observed 1-5  spectral emission from O(3P) + H2O(X1A1) collisions. Another important result is that OH(X2) products are formed in two distinct ro-vibrational distributions. The 'active' OH products are formed with the reagent O-ato...

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