Article

# Quasiclassical determination of reaction probabilities as a function of the total angular momentum.

Departamento de Química Física, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain.

The Journal of Chemical Physics (Impact Factor: 3.12). 10/2005; 123(9):94101. DOI: 10.1063/1.2009739 Source: PubMed

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**ABSTRACT:**The dynamics of the singlet channel of the Si+O2→SiO+O reaction is investigated by means of quasiclassical trajectory (QCT) calculations and two statistical based methods, the statistical quantum method (SQM) and a semiclassical version of phase space theory (PST). The dynamics calculations have been performed on the ground 1A′ potential energy surface of Dayou and Spielfiedel [J. Chem. Phys. 119, 4237 (2003)] for a wide range of collision energies (Ec = 5–400 meV) and initial O2 rotational states (j = 1–13). The overall dynamics is found to be highly sensitive to the selected initial conditions of the reaction, the increase in either the collisional energy or the O2 rotational excitation giving rise to a continuous transition from a direct abstraction mechanism to an indirect insertion mechanism. The product state properties associated with a given collision energy of 135 meV and low rotational excitation of O2 are found to be consistent with the inverted SiO vibrational state distribution observed in a recent experiment. The SQM and PST statistical approaches, especially designed to deal with complex-forming reactions, provide an accurate description of the QCT total integral cross sections and opacity functions for all cases studied. The ability of such statistical treatments in providing reliable product state properties for a reaction dominated by a competition between abstraction and insertion pathways is carefully examined, and it is shown that a valuable information can be extracted over a wide range of selected initial conditions.The Journal of Chemical Physics 05/2008; 128(17):174307-174307-16. · 3.12 Impact Factor -
##### Article: ACCURATE TIME-DEPENDENT WAVE PACKET STUDY OF THE H++LiH REACTION AT EARLY UNIVERSE CONDITIONS

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**ABSTRACT:**The dynamics and kinetics of the H+ + LiH reaction have been studied using a quantum reactive time-dependent wave packet (TDWP) coupled-channel quantum mechanical method on an ab initio potential energy surface at conditions of the early universe. The total reaction probabilities for the H+ + LiH(nu = 0, j = 0) -> H-2(+) + Li process have been calculated from 5 x 10(-3) eV up to 1 eV for total angular momenta J from 0 to 110. Using a Langevin model, integral cross sections have been calculated in that range of collision energies and extrapolated for energies below 5 x 10(-3) eV. The calculated rate constants are found to be nearly independent of temperature in the 10-1000 K interval with a value of approximate to 10(-9) cm(3) s(-1), which is in good agreement with estimates used in evolutionary models of the early universe lithium chemistry.The Astrophysical Journal 11/2012; 759(1). · 6.73 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The [image omitted] reaction on the [image omitted] state potential energy surface is investigated using the quantum mechanical real wave packet method. The state-to-state and state-to-all reaction probabilities for total angular momentum J = 0 have been calculated. The probabilities for J > 0 have been calculated by means of the simple J-shifting method. The initial state selected integral cross-sections and rate coefficients have been calculated. The state-to-state, state-to-all reaction probabilities and the reaction cross-section do not manifest any significant oscillations and the initial state selected reaction rate constants are sensitive to the temperature.Molecular Physics 01/2011; 109(5). · 1.67 Impact Factor

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