Accurate time dependent wave packet calculations for the N + OH reaction

Bulut, Niyazi; Roncero, Octavio; Jorfi, M.; Honvault, Pascal

doi:10.1063/1.3633240

Cited by 22 publications

(23 citation statements)

References 40 publications

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“…They exhibit sharp and dense resonance structures in the observed initial state selected reaction probabilities. 30,[33][34][35][36][37] The initial state-selected integral cross sections exhibit a maximum value at the onset and the reaction rate decreases with increasing temperature beyond ∼50 K. 30,[33][34][35][36][37][38][39][40][41] …”

Section: Initial State-selected Rate Constantsmentioning

confidence: 98%

Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state

Rao

Goswami

Mahapatra

et al. 2013

The Journal of Chemical Physics

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Quantum state-selected dynamics of C((3)P) + OH (X(2)Π) → CO(a(3)Π) + H ((2)S) reaction on its first excited electronic potential energy surface (1(2)A(")) is examined here using a time-dependent wave packet propagation approach. All partial wave contributions for the total angular momentum, J = 0-95, are included to obtain the converged cross sections and initial state-selected rate constants in the temperature range of 10-500 K. The reaction probability, as a function of collision energy, exhibits dense oscillatory structures owing to the formation of resonances during collision. These resonance structures also persist in reaction cross sections. The effect of reagent rotational and vibrational excitation on the dynamical attributes is examined and discussed. Reagent rotational excitation decreases the reactivity whereas, vibrational excitation of the reagent has minor effects on the reactivity. The results presented here are in good accord with those obtained using the time-independent quantum mechanical and quasi-classical trajectory methods.

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Section: Initial State-selected Rate Constantsmentioning

confidence: 98%

Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state

Rao

Goswami

Mahapatra

et al. 2013

The Journal of Chemical Physics

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“…The CO formation reaction via C + OH has an exothermicity of −6.5 eV and a rate of k chem ∼ 10 −10 cm 3 s −1 (Zanchet et al 2007). The excess energy is used to pump CO to high vibrational levels with a maximum population at v = 10 ( Bulut et al 2011). The formation of CO constitutes a pumping mechanism for CO. We can compare the efficiency of the chemical pumping with the efficiency of the population of the v = 1 level by collisions with atomic hydrogen by noting that OH reaches a maximum abundance of ∼10 −6 (Fig.…”

Section: Co Ro-vibrational Level Excitationmentioning

confidence: 99%

Radiation thermo-chemical models of protoplanetary discs

Thi

Kamp²,

Woitke

et al. 2013

A&A

110

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Context. The carbon monoxide (CO) ro-vibrational emission from discs around Herbig Ae stars and T Tauri stars with strong ultraviolet emissions suggests that fluorescence pumping from the ground X 1 Σ + to the electronic A 1 Π state of CO should be taken into account in disc models. Aims. We wish to understand the excitation mechanism of CO ro-vibrational emission seen in Herbig Ae discs, in particular in transitions involving highly excited rotational and vibrational levels. Methods. We implemented a CO model molecule that includes up to 50 rotational levels within nine vibrational levels for the ground and A-excited states in the radiative-photochemical code ProDiMo. We took CO collisions with hydrogen molecules (H 2 ), hydrogen atoms (H), helium (He), and electrons into account. We estimated the missing collision rates using standard scaling laws and discussed their limitations. We tested the effectiveness of ultraviolet (UV) fluorescence pumping for the population of high-vibrational levels (v = 1-9, J = 1-50) for four Herbig Ae disc models (disc mass M disc = 10 −2 , 10 −4 and inner radius R disc = 1, 20 AU). We tested the effect of infrared (IR) pumping on the CO vibrational temperature and the rotational population in the ground vibrational level. Results. UV fluorescence and IR pumping impact on the population of ro-vibrational v > 1 levels. The v = 1 rotational levels are populated at rotational temperatures between the radiation temperature around 4.6 μm and the gas kinetic temperature. The UV pumping efficiency increases with decreasing disc mass. The consequence is that the vibrational temperatures T vib , which measure the relative populations between the vibrational levels, are higher than the disc gas kinetic temperatures (suprathermal population of the vibrational levels). The effect is more important for low-density gases because of lower collisional de-excitations.The UV pumping is more efficient for low-mass (M disc < 10 −3 M ) than high-mass (M disc > 10 −3 M ) discs. Rotational temperatures from fundamental transitions derived using optically thick 12 CO v = 1−0 lines do not reflect the gas kinetic temperature. Uncertainties in the rate coefficients within an order of magnitude result in variations in the CO line fluxes up to 20%. CO pure rotational levels with energies lower than 1000 K are populated in local thermodynamic equilibrium but are sensitive to a number of vibrational levels included in the model. The 12 CO pure rotational lines are highly optically thick for transition from levels up to E upper = 2000 K. The model line fluxes are comparable with the observed line fluxes from typical Herbig Ae low-and high-mass discs.

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“…The astrophysical interest of reactions between free radicals has motivated an ample list of recent studies of collisions between open-shell atoms such as C( 3 P), [1][2][3][4][5][6][7] N( 4 S), [8][9][10] F( 2 P), [11][12][13][14] O( 3 P), [15][16][17][18] or S( 3 P) (Refs. 19 and 20) with the hydroxyl radical OH( 2 ).…”

Section: Introductionmentioning

confidence: 99%

“…Recent examples of the possibilities of such approaches have been reported for the N+OH reaction. 9,10 In those works, quasi-classical trajectory (QCT) and quantum mechanical (QM) calculations were performed to obtain reaction probabilities, cross sections, and rate constants. A comparison with measured rate constants was also presented in Ref.…”

Section: Introductionmentioning

confidence: 99%

An accurate study of the dynamics of the C+OH reaction on the second excited 14A″ potential energy surface

Zanchet

González‐Lezana

Roncero

et al. 2012

The Journal of Chemical Physics

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Dynamics study of the OH + NH3 hydrogen abstraction reaction using QCT calculations based on an analytical potential energy surface J. Chem. Phys. 138, 214306 (2013) The dynamics of the C( 3 P)+OH(X 2 ) → CO(a 3 )+H( 2 S) on its second excited potential energy surface, 1 4 A , have been investigated in detail by means of an accurate quantum mechanical (QM) time-dependent wave packet (TDWP) approach. Reaction probabilities for values of the total angular momentum J up to 50 are calculated and integral cross sections for a collision energy range which extends up to 0.1 eV are shown. The comparison with quasi-classical trajectory (QCT) and statistical methods reveals the important role played by the double well structure existing in the potential energy surface. The TDWP differential cross sections exhibit a forward-backward symmetry which could be interpreted as indicative of a complex-forming mechanism governing the dynamics of the process. The QM statistical method employed in this study, however, is not capable to reproduce the main features of the possible insertion nature in the reactive collision. The ability to stop individual trajectories selectively at specific locations inside the potential energy surface makes the QCT version of the statistical approach a better option to understand the overall dynamics of the process.

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Accurate time dependent wave packet calculations for the N + OH reaction

Cited by 22 publications

References 40 publications

Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state

Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state

Radiation thermo-chemical models of protoplanetary discs

An accurate study of the dynamics of the C+OH reaction on the second excited 14A″ potential energy surface

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