Stereodynamics study of reactions N（2D）＋HD→NH＋D and ND＋H

The product polarizations of the title reactions are investigated by employing the quasi-classical trajectory （QCT） method. The four generalized polarization-dependent differential cross-sections （PDDCSs） （2π/σ）（dσ00/dωt）, （2π/σ）（dσ20/dωt）, （2π/σ）（dσ22＋/dωt）, and （2π/σ）（dσ21-/dωt） are calculated in the centre-of-mass frame. The distribution of the angle between κ and j＇, P（θr）, the distribution of the dihedral angle denoting κ-κ＇-j＇ correlation, P（Фr）, as well as the angular distribution of product rotational vectors in the form of polar plots P（θr, Фr） are calculated. The isotope effect is also revealed and primarily attributed to the difference in mass factor between the two title reactions.

Effects of the vibrational and rotational excitation of reagent on the stereodynamics of the reaction S (3P) ＋ H2→ SH ＋ H

Quasiclassical trajectory （QCT） calculations are first carried out to study the stereodynamics of the S （3p） ＋ H2 → SH ＋ H reaction based on the ab initio 13Atr potential energy surface （PES） （Lii etal. 2012 J. Chem. Phys. 136 094308）. The QCT-calculated reaction probabilities and cross sections for the S ＋ H2 （v = 0, j = 0） reaction are in good agreement with the previous quantum mechanics （QM） results. The vector properties including the alignment, orientation, and polarization- dependent differential cross sections （PDDCSs） of the product SH are presented at a collision energy of 1.8 eV. The effects of the vibrational and rotational excitations of reagent on the stereodynamics are also investigated and discussed in the present work. The calculated QCT results indicate that the vibrational and rotational excitations of reagent play an important role in determining the stereodynamic properties of the title reaction.

Quasi-classical trajectory study of the stereodynamics of a Ne+H_2^+→NeH^++H reaction

We have carried out a quasi-classical trajectory calculation for the reaction ofNe ＋ H2＋ （v = 0, j = 1） → NeH＋ ＋ H on the ground state （12AI） using the LZHH potential energy surface constructed by L/i et al. [Lu S J, Zhang P Y, Han K L and He G Z 2010 J. Chem. Phys. 132 014303]. Differential cross sections at many collision energies indicate that the reaction is dominated by forward-scattering. In addition, the Nell＋ product shows rotationally hot and vibrationally cold distributions. Stereodynamical results indicate that the products are strongly polarized in the direction perpendicular to the scattering plane and that the products rotate mainly in planes parallel to the scattering plane.

Quasi-classical trajectory study of the isotope effect on the stereodynamics in the reaction H(~2S) + CH(X^2Π;u= 0,j= 1) → C(~1D) + H_2(X^1Σ_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.

Theoretical study of the stereodynamics of the He+HD^+ reaction

This paper investigates the stereodynamics of the reaction He＋HD^＋ by the quasi-classical trajectory （QCT） method using the most accurate AQUILANTI surface [Aquilanti et al 2000 Mol. Phys. 98 1835]. The distribution P（Фτ） of dihedral angle and the distribution P（θτ） of angle between k and j＇ have been presented at three different collision energies. Four generalized polarization-dependent differential cross-sections （2π/σ）（dσ00/dωt）, （2π/σ）（dσ20/dωt）, （2π/σ）（dσ22/dωt）, （（2π/σ）（dσ21-/dωt） are also calculated. Some interesting results are obtained from the comparison of the stereodynamics of the title reaction at different collision energies.

Influence of the reagent vibration on the stereodynamics of the reactions D^-+H_2 and H^-+D_2

Employing the quasi-classical trajectory method and the potential energy surface of Panda and Sathyamurhy [Panda A N and Sathyamurthy N 2004 J. Chem. Phys. 121 9343], the effect of the reagent vibration on vector correlation of the ion-molecule reactions D- ＋ H2 and H- ＋ D2 is studied at a collision energy of 35.7 kcal/mol. Four generalized polarization-dependent differential cross sections （2π/σ） （dσ00/dωt）, （2π/σ） （dσ20/dσ20）, （27π/σ） （dσ22＋/dwt）, and （2π/σ）（dπ/σ） are presented in the centre-of-mass reference frame, separately. At the same time, the effects on the product angular distributions P（θr）, P（~r） and P（Oφ） of the title reactions are also analysed. The calculated results show that the scattering tendencies of the product HD, the alignment and the orientation of j^1 sensitively depend on reagent molecule vibration.

Energy and rotation-dependent stereodynamics of H(~2S) + NH(a^1?) → H_2(X^1Σ_g^+) + N(~2D) reaction

Quasi-classical trajectory calculations are performed to study the stereodynamics of the H（~2S） ＋ NH（a^1？） →H_2（X^1Σ_g~＋） ＋ N（~2D） reaction based on the first excited state NH_2（1~2A＇） potential energy surface reported by Li et al.[Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k-k＇ distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k-k＇ distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j＇ of the product H_2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment.

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 （X^3 ∑^-, v = 0, j = 0）→ N（^4S） ＋ H2 on the ground state ^4A″ potential energy surface （PES） constructed by Zhai and Han [2011 Jr. 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-kt 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（Or） is strongly dependent on the collision energy below the lower collision energy （about 11.53 kcal/mol）. In addition, the P（（Pr） 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.

Theoretical study of stereodynamics for the D'+ DS(v=0,j=0) → D'D + S abstraction reaction

Quasiclassical trajectory （QCT） calculations have been performed for the abstraction reaction, Dt＋ DS（v = 0, j = 0） → D＇D ＋ S on a new LZHH potential energy surface （PES） of the adiabatic 3A＇＇ electronic state [Lü et al. 2012 J. Chem. Phys. 136 094308]. The collision energy effect on the integral cross section and product polarization are studied over a wide collision energy range from 0.1 to 2.0 eV. The cross sections calculated by the QCT procedure are in good accordance with previous quantum wave packet results. The three angular distribution functions, P（θr）, P（φr）, and P（θr,φr）, together with the four commonly used polarization-dependent differential cross sections （（2 π/σ） （ d σ00 / d ω1）, （2π/σ） （d σ20 / d ω1）, （2π/σ）（dσ22＋/dω1）, （2π/σ）（dσ21-/dω1）） are obtained to gain insight into the chemical stereodynamics of the title reaction. Influences of the collision energy on the product polarization are exhibited and discussed.

A theoretical study of the stereodynamics on the abstraction reactions H/D+HS/DS

The quasi-classical trajectory （QCT） method is employed to calculate the stereodynamics of the abstraction reactions H/D ＋ HS/DS based on an accurate potential energy surface [Lti S J, Zhang P Y, Han K L and He G Z 2012 J. Chem. Phys. 136 094308]. The reaction cross sections of the title reaction are computed, and the vector correlations for different collision energies and different initial vibrational states are presented. The influences of the collision energy and reagent vibration on the product polarization are studied, and the product polarizations of the title reactions are found to be distinctly different, which arises from the different mass factors, collision energies, and reagent vibrational states.

The collision energy effect on the stereodynamics of the Ca + HCl→CaCl + H reaction

The stereodynamics of the reaction of Ca ＋ HCl are calculated at three different collision energies based on the potential energy surface [Verbockhaven G et al. 2005 J. Chem. Phys. 122 204307] using quasi-classical trajectory theory. The polarization-dependent differential cross sections （PDDCSs） （2π/σ ）（dσ 00 /dω t ）, （2π/σ ）（dσ 20 /dωt ）, （2π/σ ）（dσ 22＋ /dωt ）, （2π/σ ）（dσ 21 /dω t ） and the distributions of P（θ r ）, P（φr ）, and P（θr ,φr ） are calculated. The results indicate that the rotational polarization of the CaCl product presents different characteristics for the different collision energies, and the effects of the collision energy on the vector potential, including the alignment, orientation, and PDDCSs, are not obvious.

Theoretical study of stereodynamics for the reaction O(3P) ＋D2 (v=0, j=0) →OD＋D and isotope effect

Quasi-classical trajectory （QCT） calculations have been performed to study the product polarization behaviours in the reaction O（3p） ＋ D2 （v = 0, j = 0） → OD ＋ D. By running trajectories on the 3A′ and 3A″potential energy surfaces （PESs）, vector correlations such as the distributions of the polarization-dependent differential cross sections （PDDCSs）, the angular distributions of P（θr） and P（Фr） are presented. Isotope effect is discussed in this work by a comprehensive comparison with the reaction O（3p） ＋ H2 （v = 0, j = 0） → H ＋ H. Common characteristics as well as differences are discussed in product alignment and orientation for the two reactions. The isotope mass effect differs on the two potential energy surfaces： the isotope mass effect has stronger influence on P（θr） and PDDCSs of the 3A′ PES while the opposite on P（Фr） of the 3A′ potential energy surface.

Stereodynamics of the reactions: F+H_2/HD/HT→FH+H/D/T

Among many kinds of ways to study the properties of atom and molecule collision, the quasi-classical trajectory （QCT） method is an effective one to investigate the molecular reaction dynamics. QCT calculations have been carried out to investigate the stereodynamics of the reactions F ＋ H2/HD/HT→FH ＋ H/D/T, which proceed on the lowest-lying electronic states of the FH2 system based on the potential energy surface （PES） of the 1^ 2A＇ FH2 ground state. Although the QCT method cannot describe all quantum effects in the process of the reaction, it has unique advantages when facing a three-atoms system or complicated polyatomic systems. Differential cross sections （DCSs） and three angle distribution functions P（Or）, P（Фr）, P（Or, Фr） on the PES at the collision of 2.74 kcal/mol have been investigated. The isotope effect becomes more obvious with the reagent molecule H2 turning into HD and HT. P（θr, （Фr）, as the joint probability density function of both polar angles θr and Фr, can reflect the properties of three-dimensional dynamic more intuitively.

Theoretical study of stereodynamics for the N+H_2/D_2/T_2 reactions

The effects of isotopic variants on stereodynamic properties for the title reactions have been investigated using a quasi-classical trajectory method based on the first excited state NH2（I^2A＇） potential energy surface [Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644]. The forward–backward symmetry scattering of the differential cross section can be observed, which demonstrates that all these reactions follow the insertion mechanism. Three angle distribution functions P（θr）, P（φr）, and P（θr, φr） with different collision energies and target molecules H2/D2/T2 are calculated. It is shown that the product rotational angular momentum is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The title reaction is mainly governed by the ＂in-plane＂ mechanism through the calculated distribution function P（θr, φr）. The observable influences on the rotational polarization of the product by the isotopic substitution of H/D/T can be demonstrated.

Effects of collision energy and rotational quantum number on stereodynamics of the reactions:H(~2S)+NH(v=0,j=0,2,5,10)→N(~4S)+H_2

The stereodynamical properties of H（^2S） ＋ NH（v = 0,j = 0,2,5,10）→N（^4S） ＋ H2 reactions are studied in this paper by using the quasi-classical trajectory（QCT） method with different collision energies on the double many-body expansion（DMBE） potential energy surface（PES）（Poveda L A and Varandas A J C 2005 Phys.Chem.Chem.Phys.7 2867）.In a range of collision energy from 2 to 20 kcal/mol,the vibrational rotational quantum numbers of the NH molecules are specifically investigated on v = 0 and j = 0,2,5,10 respectively.The distributions of P（θr）,P（φr）,P（θr,φr）,（2π/σ）（dσ（00）/dωt）differential cross-section（DCSs） and integral cross-sections（ICSs） are calculated.The ICSs,computed for collision energies from 2 kcal/mol to 20 kcal/mol,for the ground state are in good agreement with the cited data.The results show that the reagent rotational quantum number and initial collision energy both have a significant effect on the distributions of the k-j＇,the k-k＇-j＇,and the k-k＇ correlations.In addition,the DCS is found to be susceptible to collision energy,but it is not significantly affected by the rotational excitation of reagent.

Stereodynamics study of the H'(~2S)+NH(X^3Σ^-)→N(~4S)+H_2 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.

Quasiclassical trajectory theoretical study on the chemical stereodynamics of the O(~1D)+H_2→OH+H reaction and its isotopic variants (HD, D_2)

The quasiclassical trajectory （QCT） method is used to study stereodynamic information about the reaction O （1D）＋H2 --4OH＋H on the DK （Dobbyn and Knowles） （llA;） ab initio potential energy surface （PES）. A wide scale of collision energy （Ec） from 0.05 eV to 0.5 eV is considered in the dynamic calculations. To reveal the rovibrational excitation effect, calculations at a collision energy of 0.52 eV are carried out for the v = 0 - 5, j = 0 and v = 0, j -- 0 - 15 initial states. The two popularly used polarization-dependent differential cross sections （PDDCSs）, dtY0o/doh （0, 0） and dtra0/dtot（2, 0）, and two angular distributions, P（φr） and P（φr） are calculated to obtain an insight into the alignment and the orientation of the product molecules. From the calculations, we can obtain that the alignment of the OH product is weaker at high collision energy and becomes stronger with the increase of initial vibrational level, and it is almost insensitive to the initially rotational excitation. Influences of the mass values of isotopes （HD, D2） on the stereodynamics are also shown and discussed. Comparisons between available theoretical results and experimental results are made and discussed.

Stereodynamics of the reactions Ne+H_2^+/Ne+D_2^+/Ne+T_2

The vector correlations between products and reagents for the reactions Ne＋H2＋, Ne＋D2＋, and Ne＋T2＋ are calculated by means of the quasi-classical trajectory method on a new potential energy surface constructed by Lfi et al, [J. Chem. Phys. 2010 132, 014303]. The polarization-dependent differential cross-sections （27π/σ）（dσ00/dωt）, （2π/σ）（dσ20/dwt）, （27π/σ）（dσ22＋/dwt）, and （2π/σ）（dσ21-/dwt）, and the distributions of P（θr）, P（φ）, and P（θr, Cr） are calculated. The isotopic effect, which is associated with the difference in mass factor among the three reactions, is revealed.

Influence of reagent vibration on the stereodynamics of the Li+HF→LiF+H reaction

We investigate the influence of reagent vibration on the stereodynamics of the title reaction by the quasi-classmal trajectory on the Aguado-Paniagua2-potential energy surface developed by Aguado et al. （J. Chem. Phys. 1997 106 1013）. The cross sections and reaction probability as functions of the reagent vibration are calculated in the centre-of- mass frame. The product angular distributions of p（Фr）, p（Фr）, and p（Фr, Фr）, which reflect the vector correlation, are also presented and discussed. The results indicate that the vector properties are sensitively affected by the vibrational excitation.

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 （12A＇） 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（0r）, P（~r）, and P（Or, Cr）, 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 PDDCS00 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.