Stereodynamics in reaction O（1D） ＋ CH4 〉OH ＋ CH3

A theoretical study of the stereodynamics for reaction O(1D) + CH4→OH + CH3 has been carried out using the quasiclassical trajectory method(QCT) on a potential energy surface structured by Gonzalez et al. The integral cross sections(ICSs), differential cross sections(DCSs) and product rotational angular momentum polarization have been calculated. With the collision energy increasing, the ICS decreases. There is no threshold energy, because no barrier is found on the minimum energy path. The DCS results show that the backward and forward scatterings exist at the same time. With the collision energy increasing, the dominant rotation of the product changes from the right-handed direction to the left-handed direction in planes parallel to the scattering plane. In the isotopic effect study, the decrease of the mass factor weakens the polarization degree of the rotational angular momentum vectors of the products.     

Stereodynamics study of the H′（^2S） ＋ NH（X^3∑-） 〉 N（4S） ＋ H2 reaction

The stereodynamics and reaction mechanism of the H′（^2S） ＋ NH （X^3∑^-） → N（^4S） ＋ H2 reaction are thoroughly studied at collision energies in the 0.1 eV-1.0 eV range using the quasiclassical trajectory （QCT） on the ground 4A″ potential energy surface （PES）. The distributions of vector correlations between products and reagents P（φr）, P（φr） and P（φr,φr） are presented and discussed. The results indicate that product rotational angular momentum j′ is not only aligned, but also oriented along the direction perpendicular to the scattering plane; further, the product H2 presents different rotational polarization behaviors for different collision energies. Furthermore, four polarization-dependent differential cross sections （PDDCSs） of the product He are also calculated at different collision energies. The reaction mechanism is analyzed based on the stereodynamics properties. It is found that the abstraction mechanism is appropriate for the title reaction.     

Isotope effect on the stereodynamics for the collision reaction H＋LiF（v = 0, j = 0） → HF＋Li

Stereodynamics for the reaction H+LiF(v=0, j=0) → HF+Li and its isotopic variants on the ground-state (1 2 A′) potential energy surface (PES) are studied by employing the quasi-classical trajectory (QCT) method. At a collision energy of 1.0 eV, product rotational angular momentum distributions P (θr), P (φr), and P (θr ,φr), are calculated in the center-of-mass (CM) frame. The results demonstrate that the product rotational angular momentum j′ is not only aligned along the direction perpendicular to the reagent relative velocity vector k, but also oriented along the negative y axis. The four generalized polarization-dependent differential cross sections (PDDCSs) are also computed. The PDDCS 00 distribution shows a preferential forward scattering for the product angular distribution in each of the three isotopic reactions, which indicates that the title collision reaction is a direct reaction mechanism. The isotope effect on the stereodynamics is revealed and discussed in detail.     

Stereodynamics of the O（3P） with H2（D2） （ν=0,j=0） reaction

Quasi-classical trajectory theory is used to study the reaction of O(3 P) with H 2 (D 2) based on the ground 3 A″ potential energy surface (PES).The reaction cross section of the reaction O+H 2 →OH+H is in excellent agreement with the previous result.Vector correlations,product rotational alignment parameters P 2 (j · k) and several polarizeddependent differential cross sections are further calculated for the reaction.The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES,arising from various collision energies or mass factors.     

Stereodynamics of the O（^3p） with H： （D2） （v = O,j =O） reaction

Quasi-classical trajectory theory is used to study the reaction of O（3p） with H2 （D2） based on the ground 3A″ potential energy surface （PES）. The reaction cross section of the reaction O＋H2→＋OH＋H is in excellent agreement with the previous result. Vector correlations, product rotational alignment parameters （P2（j′. k）） and several polarizeddependent differential cross sections are further calculated for the reaction. The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES, arising from various collision energies or mass factors.     

The characteristics of O＋HD （v = 0, j = 0） reaction dynamics

The analytical potential energy function of HDO is constructed at first using the many-body expansion method.The reaction dynamics of O+HD(v = 0,j = 0) in five product channels are all studied by quasi-classical trajectory(QCT) method.The results show that the long-lived complex compound HDO is the dominant product at low collision energy.With increasing collision energy,O+HD → OH+D and O+HD → OD+H exchange reactions will occur with remarkable characteristics,such as near threshold energies,different reaction probabilities,and different reaction cross sections,implying the isotopic effect between H and D.With further increasing collision energy(e.g.,up to 502.08 kJ/mol),O+HD → O+H+D will occur and induce the complete dissociation into single O,H,and D atoms.     

Quasi-classical trajectory study of the isotope effect on the stereodynamics in the reaction H（2S） ＋ CH（X2∏; v=o,j= 1）→ C（1D）＋H2（X1∑g＋）

The isotope effect on the stereodynamic properties in the title reaction is investigated by a quasi-classical trajectory （QCT） method on the 11At potential energy surface at a collision energy of 23.06 kcal/mol. The angular distributions P（φr ）, P（θr）, P（θr, φr）, and the polarization-dependent generalized differential cross sections are calculated, which demonstrate the observable influences on the rotational polarization of the product by the isotopic substitution of H with D.     

Quasi-classical trajectory study of the isotope effect on the stereodynamics in the reaction H（2S） + CH（X2Π;u= 0,j= 1） → C（1D） + H2（X1Σg+）

The isotope effect on the stereodynamic properties in the title reaction is investigated by a quasi-classical trajectory(QCT) method on the 11A potential energy surface at a collision energy of 23.06 kcal/mol. The angular distributions P(θr),P(φr), P(θr, φr), and the polarization-dependent generalized differential cross sections are calculated, which demonstrate the observable influences on the rotational polarization of the product by the isotopic substitution of H with D.     

Stereodynamics study of the exchange reaction O(~3P)+CH_4 →H+OCH_3

A new London-Eyring-Polanyi-Sato potential energy surface is employed in this work to study the stereo properties of the O(3P)+CH4 →H+CH3O reaction in its rovibrationally ground state using the quasiclassical trajectory method(QCT).Our calculations are performed at a range of collision energies,Ec=1.5eV～3.5eV,and the excitation function obtained by the QCT method accords well with the experimental data.The product rotational polarization is calculated,and the product shows a strong rotational polarization in the centre-of-mass coordinate system.The orientation of the product rotational angular momenta is sensitive to the increase in collision energy,and the alignment of the product rotational angular momenta shows some of the properties of the heavy heavy-light mass combination reactions.In the isotopic substituted reaction study,when the H atoms in methane are replaced by D atoms,the rotational polarization is obviously reduced.The polarization-dependent differential cross section is also studied by this QCT calculation to provide detailed information about the rotational alignment and orientation of the product.     

The effect of collision energy on the stereodynamics of the reaction H(~2S)+NH(X~3∑~-,v = 0,j = 0)→ N(~4S)+H_2

The quasi-classical trajectory(QCT) is calculated to study the stereodynamics properties of the title reaction H(2S)+NH(X3∑-) →N(4S)+H2 on the ground state 4A' potential energy surface(PES) constructed by Zhai and Han [2011 J.Chem.Phys.135 104314].The calculated QCT reaction probabilities and cross sections are in good agreement with the previous theoretical results.The effects of the collision energy on the k-k' distribution and the product polarization of H2 are studied in detail.It is found that the scattering direction of the product is strongly dependent on the collision energy.With the increase in the collision energy,the scattering directions of the products change from backward scattering to forward scattering.The distribution of P(θr) is strongly dependent on the collision energy below the lower collision energy(about 11.53 kcal/mol).In addition,the P(φr) distribution dramatically changes as the collision energy increases.The calculated QCT results indicate that the collision energy plays an important role in determining the stereodynamics of the title reaction.     

Stereo-dynamics of the exchange reaction HaWLiHb → LiHa＋Hb and its isotopic variants

<正>The quasi-classical trajectory(QCT) method is used to calculate the stereo-dynamics of the exchange reaction H_a+LiH_b→LiH_a+H_b and its isotopic variants based on an accurate potential energy surface reported by Prudente et al.[Prudente F V,Marques J M C and Maniero A M 2009 Chem.Phys.Lett.474 18].The reactive probability of the title reaction is computed.The vector correlations and four polarization-dependent generalized differential cross sections(PDDCSs) at different collision energies are presented.The influences of the collision energy and the reagent rotation on the product polarization are studied in the present work.The results indicate that the product rotational angular momentum j’ is not only aligned,but also oriented along the direction perpendicular to the scattering plane. The product polarization distributions of the title reaction and its isotopic variants exhibit distinct differences which may arise from different mass combinations.     

Quasi-classical trajectory investigation on the stereodynamics of Li ＋ DF（v=1-6,j=0）→LiF＋D reaction

In this paper, the stereodynamics of Li ＋ DF → Li F ＋ D reaction is investigated by the quasi-classical trajectory（QCT）method on the ^2A＇ potential energy surface（PES） at a relatively low collision energy of 8.76 kcal/mol. The scalar properties of the title reaction such as reaction probability and cross section are studied with vibrational quantum number of v = 1–6. The product angular distributions P（θr） and P（φr） are presented in the same vibrational level range. Moreover, two polarization-dependent generalized differential cross sections（PDDCSs）, i.e., the PDDCS00 and PDDCS22＋are calculated as well. These stereodynamical results demonstrate sensitive behaviors to the vibrational quantum numbers.     

Theoretical prediction of the optimal conditions for observing the stereodynamical vector properties of the C（3P）＋OH （X2∏）→CO（X1S＋）＋H（2S） reaction

The best optimal initial reactant state and collision energy for observing the stereodynamical vector properties of the title reaction in the ground electronic state X2A’ potential energy surface （PES）[Zanchet et al. 2006 J. Phys. Chem. A 110 12017] are theoretically predicted using the quasi-classical trajectory （QCT） method for the first time. The calculated results reveal that the smallest value of the rotational quantum number j, larger vibrational quantum number v, and the lower strength of collision energy should be selected for offering the most obvious picture about the stereodynamical vector properties. Polarization-dependent differential cross sections and the angular momentum alignment distribution, P（θr） and P（Φr） in the center-of-mass frame, are obtained to gain an insight into the alignment and orientation of the product molecules. The rotational angular momentum vector j’ of CO is aligned to be perpendicular to reagent relative velocity k. The product polarizations align along the y axis, pointing to the positive direction of the y axis. A new method is developed to investigate massive reactions with various initial states and to further study the vector properties of the fundamental reactions in detail.     

Reaction mechanism of D + ND→N + D_2 and its state-to-state quantum dynamics

The quantum state-to-state calculations of the D + ND→N + D_2 reaction are performed on a potential energy surface of 4 A' state. The state-resolved integral and differential cross sections and product state distributions are calculated and discussed. It is found that the rotational distribution, rather than the vibrational distribution, of the product has an obvious inversion. Due to the fact that it is a small-impact-parameter collision, its product D_2 is mainly dominated by rebound mechanism, which can lead to backward scattering at low collision energy. As the collision energy increases, the forward scattering and sideward scattering begin to appear. In addition, the backward collision is also found to happen at high collision energy, through which we can know that both the rebound mechanism and stripping mechanism exist at high collision energy.     

Theoretical study of stereodynamics for the O（3P） ＋ H2 → OH ＋ H reaction

This paper employs the quasi-classical trajectory calculations to study the influence of collision energy on the title reaction on the potential energy surface of the ground ³A' triplet state developed by Rogers et al. (J. Phys. Chem. A 2000 104 2308). It calculates the product angular distribution of P(θ_r), P(φ_r) and P(θ_r, φ_r) which reflects vector correlation. The distribution P(θ_r) shows that product rotational angular momentum vectors j' of the products are strongly aligned along the relative velocity direction k. The distribution of P(φ_r) implies a preference for left-handed product rotation in planes parallel to the scattering plane. Four different polarisation-dependent cross-sections are also presented in the centre-of-mass frame. Results indicate that OH is sensitively affected by collision energies of H₂.     

Stereodynamics of the He ＋ D2^＋ → HeD^＋ ＋ D Reaction on the PALMIERI Surface

Using the quasi-classical trajectory method, the product rotational polarization of the ion-molecule reaction He^＋D2^＋ has been calculated at different collision energies on the PALMIERI potential energy surface [Palmieri et al. Mol. Phys. 98 （2000） 1835]. The distribution angle between k and j′, P（Or）, the distribution of the dihedral angle P（Фr）, and the angular distribution of product rotational vectors in the form of polar plots in θr and Фr are calculated. In addition, four polarization-dependent differential cross sections are also presented in the center-of-mass frame, respectively. The results indicate that the rotational polarization of the product HeD^＋ presents different characters for different collision energies. These discrepancies may be ascribed to the different collision energies and constructions of the potential energy surface.     

Effect of Reagent Vibrational and Rotational Excitation on the F＋H2 Reaction： Theoretical Study of the Stereodynamics Using Quasi-Classical Trajectory Method

The vector correlations in the reaction F＋H2 （v =0-3, j =0-3）→ HF（v＇, j＇）＋H are investigated using the quasi- classical trajectory method on the Stark-Werner potential energy surface at a collision energy of 1.0eV. The potential distribution P（θr） to angles between k and j＇, the distribution P（Фr） to dihedral angles, denoting k - k＇ - j＇ correlation and the polarization-dependent generalized differential cross sections, are calculated. The effect of reagent vibrational and rotational excitation on the F＋H2 reaction is discussed in detail The results suggest that the different vibrational and rotational quantum states of H2 have different influences on the product polarization.     

Mechanism analysis of reaction S~+(~2D)+H_2(X~1Σ_g~+) → SH~+(X~3Σ~-) + H(~2S) based on the quantum state-to-state dynamics

We present a state-to-state dynamical calculation on the reaction S~++ H_2→ SH~+ +H based on an accurate ~X2 A~″ potential surface. Some reaction properties, such as reaction probability, integral cross sections, product distribution, etc.,are found to be those with characteristics of an indirect reaction. The oscillating structures appearing in reaction probability versus collision energy are considered to be the consequence of the deep potential well in the reaction. The comparison of the present total integral cross sections with the previous quasi-classical trajectory results shows that the quantum effect is more important at low collision energies. In addition, the quantum number inversion in the rotational distribution of the product is regarded as the result of the heavy–light–light mass combination, which is not effective for the vibrational excitation. For the collision energies considered, the product differential cross sections of the title reaction are mainly concentrated in the forward and backward regions, which suggests that there is a long-life intermediate complex in the reaction process.     

A typical slow reaction H（2S） ＋ S2（X3∑g） → SH（X2П） ＋S（3P） ona new surface： Quantum dynamics calculations

Quantum dynamics calculations for the title reaction H(2S) + S2(X3-Σg) → SH(X2Π) + S(3P) are performed by using a globally accurate double many-body expansion potential energy surface [J. Phys. Chem. A 115 5274(2011)].The Chebyshev real wave packet propagation method is employed to obtain the dynamical information, such as reaction probability, initial state-specified integral cross section, and thermal rate constant. It is found not only that there is a reaction threshold near 0.7 eV in both reaction probabilities and integral cross section curves, but also that both the probability and cross section increase firstly and then decrease as the collision energy increases. The existence of the resonance structure in both the probability and cross section curves is ascribed to the deep potential well. The calculation of the rate constant reveals that the reaction occurring on the potential energy surface of the ground-state HS2is slow to take place.     

Effect of reagent vibrational excitation and isotope substitution on the stereo-dynamics of the Ba+HF→BaF+H reaction

Based on an extended London-Eyring-Polanyi-Sato (LEPS) potential energy surface (PES), the Ba + HF reaction has been studied by the quasi-classical trajectory (QCT) method. The reaction integral cross section as a function of collision energy for the Ba + HF → BaF + H reaction is presented and the influence of isotope substitution on the differential cross sections (DCSs) and alignments of the product's rotational angular momentum have also been studied. The results suggest that the integral cross sections increase with increasing collision energy, and the vibrational excitation of the reagent has great influence on the DCS. In addition, the product's rotational polarization is very strong as a result of heavy-heavy-light (HHL) mass combination, and the distinct effect of isotope substitution on the stereodynamics is also revealed.