Differential Cross Sections and Product Rotational Polarization in A + BC Reactions Using Wave Packet Methods: H<sup>+</sup> + D<sub>2</sub> and Li + HF Examples

We present accurate quantum calculations of state-to-state cross sections for the N + OH → NO + H reaction performed on the ground 3 A global adiabatic potential energy surface of Guadagnini et al. [J. Chem. Phys. 102, 774 (1995)]. The OH reagent is initially considered in the rovibrational state v = 0, j = 0 and wave packet calculations have been performed for selected total angular momentum, J = 0, 10, 20, 30, 40,...,120. Converged integral state-to-state cross sections are obtained up to a collision energy of 0.5 eV, considering a maximum number of eight helicity components, = 0,...,7. Reaction probabilities for J = 0 obtained as a function of collision energy, using the wave packet method, are compared with the recently published time-independent quantum mechanical one. Total reaction cross sections, state-specific rate constants, opacity functions, and product state-resolved integral cross-sections have been obtained by means of the wave packet method for several collision energies and compared with recent quasi-classical trajectory results obtained with the same potential energy surface. The rate constant for OH(v = 0, j = 0) is in good agreement with the previous theoretical values, but in disagreement with the experimental data, except at 300 K.

Section: Methodsmentioning

confidence: 99%

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

Bulut

Roncero

Jorfi

et al. 2011

“…The overall agreement found for J = 0 was accompanied by the apparent failure of the statistical predictions as J increases, a feature which, however, was due to the small number of helicity components employed in the TDWP calculation. 46 The title reaction has also been investigated by means of the SQCT approach, in combination with a variety of different theoretical methods. 47 The rate coefficients in terms of the collisional energy obtained with this quasi-classical version of the SQM approach were found to diverge from purely quasi-classical trajectory (QCT) calculations rapidly beyond E c ∼ 3 × 10 −1 eV for processes initiated from different initial rotational states of H 2 .…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the D+ + H2 → HD + H+ reaction at the low energy regime by means of a statistical quantum method

González‐Lezana

Honvault

Scribano

2013

The D + +H 2 (v = 0, j = 0, 1) → HD+H + reaction has been investigated at the low energy regime by means of a statistical quantum mechanical (SQM) method. Reaction probabilities and integral cross sections (ICSs) between a collisional energy of 10 −4 eV and 0.1 eV have been calculated and compared with previously reported results of a time independent quantum mechanical (TIQM) approach. The TIQM results exhibit a dense profile with numerous narrow resonances down to E c ∼ 10 −2 eV and for the case of H 2 (v = 0, j = 0) a prominent peak is found at ∼2.5 × 10 −4 eV. The analysis at the state-to-state level reveals that this feature is originated in those processes which yield the formation of rotationally excited HD(v = 0, j > 0). The statistical predictions reproduce reasonably well the overall behaviour of the TIQM ICSs at the larger energy range (E c ≥ 10 −3 eV). Thermal rate constants are in qualitative agreement for the whole range of temperatures investigated in this work, 10-100 K, although the SQM values remain above the TIQM results for both initial H 2 rotational states, j = 0 and 1. The enlargement of the asymptotic region for the statistical approach is crucial for a proper description at low energies. In particular, we find that the SQM method leads to rate coefficients in terms of the energy in perfect agreement with previously reported measurements if the maximum distance at which the calculation is performed increases noticeably with respect to the value employed to reproduce the TIQM results. © 2013 AIP Publishing LLC.

“…25 The L-shaped grid method saves a large number of grid points, as compared with a conventional rectangular grid, which makes this RCB wave packet method particularly attractive and presents an efficient alternative to the PCB approaches. [14][15][16] In 2006, Gómez-Carrasco and Roncero 26 developed an coordinate transform method to extract state-to-state information in one product channel, 27 also from the TDWP propagated in reactant Jacobi coordinates. By careful numerical testing with several reactive scattering systems, these authors reached a conclusion that their RCB method is generally more efficient than the PCB method, especially for J Ͼ 0 cases.…”

Section: Introductionmentioning

confidence: 99%

Extraction of state-to-state reactive scattering attributes from wave packet in reactant Jacobi coordinates

Sun

Guo

Zhang

2010

137

126

The S-matrix for a scattering system provides the most detailed information about the dynamics. In this work, we discuss the calculation of S-matrix elements for the A + BC→ AB+ C, AC+ B type reaction. Two methods for extracting S-matrix elements from a single wave packet in reactant Jacobi coordinates are reviewed and compared. Both methods are capable of extracting the state-to-state attributes for both product channels from a single wave packet propagation. It is shown through the examples of H + HD, Cl+ H 2 , and H + HCl reactions that such reactant coordinate based methods are easy to implement, numerically efficient, and accurate. Additional efficiency can be gained by the use of a L-shaped grid with two-dimensional fast Fourier transform.