Theoretical study of the stereo-dynamics of the reaction H+FO→OH+F

Vibrational excitation influence on the H + BrO → HBr + O reaction: a quasi-classical trajectory investigation

Quasi-classical trajectory calculations are employed to investigate the vibrational excitation effect on the scalar and vector properties of the H + BrO → HBr + O reaction using a X1A′ state ab initio potential energy surface (J. Chem. Phys. 2000, 113, 4598). The reaction probability, cross section, and rate constant are carried out with the effect of the collision energy (Ecol = 0.1–6 kcal/mol) and vibrational levels (v = 0–3). A significant vibrational dependency has been observed in the reaction probability and cross section at a relatively low collision energy area and has also been found in a low-temperature (T < 150 K) region of the rate constant. In addition, two product angular distributions, P(θr) and P(ϕr), and two generalized polarization-dependent differential cross sections, PDDCS00 and PDDCS20, are calculated as well. All of these scalar and vector properties have shown sensitive behaviors to the vibrational levels.

Reagent vibrational, rotational and isotopic effects on stereodynamics of the H + OCl → OH + Cl reaction

The quasi-classical trajectory method has been employed to investigate the initial vibrational and rotational effects of the title reaction on an improved ab initio potential energy surface for the 11A′ state. Meanwhile, isotopic effect has also been studied at collision energy of 19 kcal/mol. The product rotational alignment factor 〈P2(j′ • k)〉, angular distributions of P(ϕr), P(θr) and the generalized polarization dependent differential cross-sections have been calculated. The- results show that the reagent vibrational excitation generally strengthens the product alignment perpendicular to the reagent relative velocity vector k and affects the product scattering preference, and the rotational excitation has the same trend from j = 0 to 2 except for the higher excitation of j = 3. Further, the substitution of atom H with D leads to a stronger product alignment while changes some stereodynamical properties subtly.

Energy-dependent stereodynamics for the H(2S)+NH(X3)→H2(X1Σg+)+N(4S) reaction on the improved ZH potential energy surface

In this work, quasi-classical trajectory (QCT) calculations have been first carried out for the title reaction on a new global potential energy surface for the lowest quartet electronic state, 4A″. The average rotational alignment factor [P2(j'·k)] as a function of collision energy and the two commonly used polarization dependent generalized differential cross sections PDDCS00, PDDCS20, have been calculated in the center-of-mass (CM) frame, separately. Three angular distributions, P(θr), P(φr), and P(θr, φr) are also calculated to gain insight into the alignment and the orientation of the product molecules. Calculations show that the average rotational alignment factor on the ZH PES is almost invariant with collision energies. The distributions of P(θr) and P(φr) derived from the title reaction indicate that the product polarization is strong. Validity of the QCT calculation has been examined and proven in the comparison with the quantum-wave-packet calculation results. Comparisons with available quasi-classical trajectory results are made and discussed.

THEORETICAL STUDY OF THE STEREODYNAMICS OF THE N(4S) + D2 → ND + D REACTION ON THE DMBE SURFACE

Utilizing the quasiclassical trajectory method, the product rotational polarization of the reaction N(4S) + D2 → ND + D has been calculated at different collision energies on the DMBE potential energy surface [Poveda LA et al., Phys Chem Chem Phys7:2867, 2005]. The distribution of the angle between k and j′, P(θr), the distribution of dihedral angle denoting k–k′–j′ correlation, P(ϕr), as well as the angular distribution of product rotational vectors in the form of polar plots P(θr, ϕr) are calculated. In addition, the four commonly used polarization-dependent differential cross sections, dσ00/dωt, dσ20/dωt, dσ22+/dωt, and dσ21-/dωt with ωt being the polar coordinates of the product velocity k′, are calculated in the center-of-mass frame. The effects of the collision energy on the product polarization are presented and discussed. In comparison with the result of Yu et al. [Yu YJ et al., Chin Phys B20:123402, 2011], significant isotope effects on the stereodynamics of N(4S) + D2(H2) → ND(H) + D(H) have also been revealed.

EFFECT OF THE REACTANT ALIGNMENT ON STEREODYNAMICS FOR THE REACTION F + OH

Quasi-classical trajectory (QCT) calculations are performed for the reaction F + OH → HF + O based on the adiabatic potential-energy surface (PES) of the 13A″ triplet state. The reaction probability as a function of incident angle has been presented. The differential cross sections (DCSs), the distribution of angle between k and j′, P(θr) and the distribution of dihedral angle denoting k – k′ – j′ correlation, P(ϕr) have also been calculated at the different incident angles in the center-of-mass (CM) frame, respectively. The effects of reactant alignment on stereodynamics of the reaction are firstly revealed, which provides the theoretical foundation for the related experiment and enriches the theories of the stereodynamics.

QUASI-CLASSICAL STUDY OF STEREO-DYNAMICS FOR THE REACTION C + CH → C2 + H ON THE 12A′ POTENTIAL ENERGY SURFACE

The quasi-classical trajectory (QCT) method and the 12A′ potential energy surface (PES) [Boggio-Pasqua et al., Phys Chem Chem Phys2:1693, 2000] have been employed to study the stereo-dynamics of the reaction C + CH (v = 0, j) → C2 + H at different collision energies over the range of 0.01–0.6 eV and for different rotational quantum number j = 0 - 3. The reactive total cross section with initial revibrational state of v = 0 and j = 0 as a function of collision energy is presented and compared with the quantum mechanics results. The forward-backward asymmetry phenomenon has been found in the angular distribution of the products. The calculated distribution of P(θr) indicates a strong product alignment perpendicular to k, but this kind of product alignment is found to be rather insensitive to the collision energy. The calculated distribution of P(ϕr) revealed that at low collision energy the products tend to be oriented along the negative direction of the y-axis, while at high collision energy, this product orientation tends to be pointed to the positive direction of the y-axis. Such product orientation tends generally to become stronger with the increase of collision energy. Further, product polarization (i.e. orientation and alignment) becomes weak with high rotational excitation of the reagent CH molecule.

THEORETICAL STUDY OF STEREO-DYNAMICS FOR THE REACTION C(3P) + CH(2II) → C2 + H ON THE THREE LOWEST POTENTIAL ENERGY SURFACES

Based on the global three-dimensional adiabatic potential surfaces (PESs) 12 A ′, 22 A ′, 12 A ″ [Boggio-Pasqua et al., Phys Chem Chem Phys2:1693, 2000], the stereo-dynamics of the reaction C + CH → C 2 + H has been investigated by using the quasi-classical trajectories (QCT) method. The four polarization-dependent differential cross sections (PDDCSs) and the angular distributions of P(θr), P(ϕr), P(θr, ϕr) have been calculated at the collision energy 0.1 eV on the three PESs, respectively. The calculated results indicate that the distribution of the product C2 is backward-forward scattering on the 12 A ′ and 12 A ″ PESs and backward scattering on the 22 A ′ PES. The product rotational angular momentum is strongly aligned along the perpendicular direction to the reagent relative velocity k on the three PESs. The orientation of the product C 2 rotational angular momentum tends to point to the positive direction of the y-axis on the 12 A ′ PES but the negative direction on the 22 A ′ and 12 A ″ PESs.

Quasi-classical trajectory study of the O(1D) + HF reaction dynamics on 11A′ potential energy surface

The quasi-classical trajectory (QCT) calculations for the title reaction were carried out using the recently developed, accurate potential energy surface (PES) of the [Formula: see text] singlet state of the OHF system The integral cross section and the product rotational alignment factor [Formula: see text] were calculated as a function of collision energy. In addition, I discovered the effect of isotopic substitution on stereodynamics for the title reaction, and the influence of the rotation excitation of the reagent on stereodynamics is also presented. Both the scalar and vector properties of the reaction O(1D) + HF → OH + F(2P) are studied in this paper. It was found that the reaction is mainly controlled by an indirect reaction mechanism, and that the deep noncollinear insertion HOF well has a great impact on the dynamics of the reaction. The conclusions drawn in this paper will draw from references to similar reactions, and provide a theoretical foundation for related experiments.

Nonadiabatic state-to-state reactive collisions among open shell reactants with conical intersections: the OH((2)Pi) + F((2)P) example

Accurate wave packet calculations on the OH((2)Pi) + F((2)P) → O((3)P) + HF((1)Sigma(+)) reactive collisions are performed using a recently proposed coupled diabatic states. Adiabatic and nonadiabatic dynamics are compared in detail, analyzing the final state distribution of products. It is found that with the new surfaces a significant increase of the rate constant is obtained, with noticeable nonadiabatic effects. The inclusion of the spin-orbit splittings for the calculation of the electronic partition function produces an important increase of the reaction rate constants, yielding a rather good agreement with the experimental results. It is also concluded that spin-orbit couplings are also necessary in the entrance channel to describe this reaction.

A quasi-classical trajectory (QCT) study of the H + OF reaction stereodynamics

Based on the global three-dimensional adiabatic potential surface of the 13A′ excited electronic state (J. Chem. Phys. 2005, 123, 114310) of the OHF system, we investigated the H + OF → OH + F/HF + O reaction stereodynamics by using the quasi-classical trajectory (QCT) method. The four polarization-dependent differential cross sections (PDDCSs) and the three angular distributions P(θr), P([Formula: see text]), P(θr, [Formula: see text]) were calculated at a low collision energy of 0.48 eV for both product channels. The results indicated that the products are backward-scattering on the triplet state, and the product rotational angular momenta are aligned or oriented. Moreover, there is a remarkable difference between the polarization behaviors of the two product channels. Product orientation exhibited by the OH + F channel is found to be absent in the HF + O channel at this collision energy albeit the latter shows stronger alignment along the direction perpendicular to the reagent relative velocity k than OH + F.