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.     

Quasi-classical trajectory study of collision energy effect on the stereodynamics of H + Br O → O + HBr reaction

Quasi-classical trajectory(QCT) studies on the stereodynamics of H + Br O → O + HBr reaction have been performed on the X1A′state of ab initio potential energy surface by Peterson [Peterson K A 2000 J. Chem. Phys. 113 4598] in a collision energy range from 0 kcal/mol to 6 kcal/mol. Two of the polarization-dependent generalized differential cross sections(PDDCSs),(2π /σ)( dσ00/ dωt)(PDDCS00) and(2π /σ)( dσ20/ dωt)(PDDCS20) are considered. The rotational polarizations of these products show sensitive behaviors to the calculated collision energy range. Furthermore, in order to gain more knowledge about vector correlations, the product angular distribution, P(θr), and the dihedral angle, P(φr),are calculated, and the results indicate that both the rotational alignment and orientation of the product are enhanced as collision energy increases.     

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.     

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.     

Theoretical study of stereodynamics for reaction O(3P)+HCl

<正>The vector correlation between products and reagents for reaction O(~3P)+HCl→OH+Cl is studied using a quasiclassical trajectory(QCT) method on the benchmark potential energy surface of the ground ~3A" state[Ramachandran and Peterson,J.Chem.Phys.119(2003)9550].The generalised differential cross section(2π/σ)(dσ_(00)/dω_t) is presented in the centre of mass frame.The distribution of dihedral angles,P(φr),and the distribution of angles between k and j', P(θ_r),are calculated.The influence of the collision energy and the influence of the reagent rotation and vibration on the product polarization are studied in the present work.The calculated results indicate that the rotational polarization of the product molecule is almost independent of collision energy but sensitive to the reagent rotation and vibration.     

Theoretical prediction of energy dependence for D+BrO→DBr+O reaction:The rate constant and product rotational polarization

A quasi-classical trajectory(QCT) calculation is used to investigate the vector and scalar properties of the D + Br O → DBr + O reaction based on an ab initio potential energy surface(X1A state) with collision energy ranging from 0.1 kcal/mol to 6 kcal/mol. The reaction probability, the cross section, and the rate constant are studied. The probability and the cross section show decreasing behaviors as the collision energy increases. The distribution of the rate constant indicates that the reaction favorably occurs in a relatively low-temperature region(T 100 K). Meanwhile, three product angular distributions P(θr), P(φr), and P(θr, φr) are presented, which reflect the positive effect on the rotational angular momentum j' polarization of the DBr product molecule. In addition, two of the polarization-dependent generalized differential cross sections(PDDCSs), PDDCS00 and PDDCS20, are computed as well. Our results demonstrate that both vector and scalar properties have strong energy dependence.     

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.     

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(φr) of dihedral angle and the distribution P(θr) 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.     

Effect of isotope on state-to-state dynamics for reactive collision reactions ■ and ■ in ground state 1~2 A’’ and first excited 1~2 A’ potential energy surfaces

We carry out quantum scattering dynamics and quasi-classical trajectory(QCT) calculations for the O+H_2~+ reactive collision in the ground(1~2 A").nd first excited(1~2 A') potential energy surface.We calculate the reaction probabilities of O+H_2~+(v=0,j=0)→OH~++H and O+H_2~+(v=0,j=0)→OH+H~+reaction for total angular momentum J=0.The results calculated by QCT are consistent with those from quantum mechanical wave packet.Using the QCT method,we generate in the center-of-mass frame the product state-resolved integral cross-sections(ICSs);two commonly used generalized polarization-dependent differential cross-sections(PDDCS s),(2π/σ)(dσ_(00)/dω_t),(2π/σ)(dσ_(20)/dω_t));and three angular distributions of the product rotational vectors,p(θ_r),P(φ_r),and p(θ_r,φ_r).We discuss the influence on the scalar and vector properties of the potential energy surface,the collision energy,and the isotope mass.Since there are deep potential wells in these two potential energy surfaces,their kinetic characteristics are similar to each other and the isotopic effect is not obvious.However,the well depths and configurations of the two potential energy surfaces are different,so the effects of isotopic substitution on the integral cross-section and the rotational polarization of product are different.     

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.     

Influence of the reagent vibration on the stereo-dynamics of the reactions D^- ＋ H2 and H^- ＋ D2

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）（dσ 00 /dωt）,（2π/σ）（dσ 20 /dωt）,（2π/σ）（dσ 22+ /dωt）,and （2π/σ）（dσ 21 /dωt） are presented in the centre-of-mass reference frame,separately.At the same time,the effects on the product angular distributions P （θr）,P （φr） and P （θr,φr） 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 sensitively depend on reagent molecule vibration.     

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.     

Effect of ro-vibrational excitation of NeH~+ on the stereodynamics for the reactions H+NeH~+(v=1-3,j=1,3,5) →H_2~++Ne

The stereodynamics of the abstraction reaction H + NeH+(v = 1-3,j = 1,3,5) → H2+ + Ne is studied theoretically with a quasi-classical trajectory method on a new ab initio potential energy surface [ S J,Zhang P Y,Han K L and He G Z 2012 J.Chem.Phys.132 014303].The effects of vibrational and rotational excitation of reagent molecules on the polarization of the product are investigated.The reaction cross sections,the distributions of P(θr),P(φr),and polarizationdependent differential cross sections(PDDCSs) are calculated.The obtained cross sections indicate that the title reaction is a typical barrierless atom(ion)-ion(molecule) reaction.The initial vibrational excitation and rotational excitation of reagent molecules have distinctly different influences on stereodynamics of the title reaction,and the possible reasons for the differences are presented.     

Effects of a reagent＇s rotational and vibrational excitations on reactionO（3p）＋ H2（v=0, 3, j = 0, 3, 5, 7, 9, 12, 15） → OH ＋ H

To investigate the effect of a reagent’s rotational and vibrational excitations on the stereo-dynamics of the reaction product, the title reaction is theoretically simulated using the quasi-classical trajectory (QCT) method on the 3 A and 3 A potential energy surfaces (PESs). The reaction cross section is considered as the only scalar property in this work at four different collision energies. Furthermore the vector properties including two polarization-dependent differential cross sections (PDDCSs), the angular distributions of product’ rotational momentum are discussed at one fixed collision energy. Effects of reagents’ rotational excitation on the reaction do exist regularly.     

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 (φr) 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 (φr) of the 3A potential energy surface.     

Vector correlations study of the reaction N(~2D) + H_2(X~1Σ_g~+) →NH(a~1?) + H(~2S) with different collision energies and reagent vibration excitations

Vector correlations of the reaction N(2D)+ H2(X1Σ+g) → NH(a1?)+ H(2S) are studied based on a recent DMBESEC PES for the first excited state of NH2[J. Phys. Chem. A 114 9644(2010)] by using a quasi-classical trajectory method.The effects of collision energy and the reagent initial vibrational excitation on cross section and product polarization are investigated for v = 0–5 and j = 0 states in a wide collision energy range(10–50 kcal/mol). The integral cross section could be increased by H2 vibration excitation remarkably based on the DMBE-SEC PES. The different phenomena of differential cross sections with different collision energies and reagent vibration excitations are explained. Particularly,the NH molecules are scattered mainly in the backward hemisphere at low vibration quantum number and evolve from backward to forward direction with increasing vibration quantum number, which could be explained by the fact that the vibrational excitation enlarges the H–H distance in the entrance channel, thus enhancing the probability of collision between N atom and H atom. A further study on product polarization demonstrates that the collision energy and vibrational excitation of the reagent remarkably influence the distributions of P(θr), P(φr), and P(θr, φr).     

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 [L 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 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.     

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) + H_2 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(θ_r),P(φ_r),P(θ_r,φ_r),(2π/σ)(dσ_(00)/dω_t)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.     

Quasi-classical trajectory study of H+LiH(v=0,1,2,j=0)→Li+H_2 reaction on a new global potential energy surface

Quasi-classical trajectory(QCT) calculations are reported for the H+LiH(v = 0–2, j = 0)→Li+H_2 reaction on a new ground electronic state global potential energy surface(PES) of the LiH_2 system. Reaction probability and integral cross sections(ICSs) are calculated for collision energies in the range of 0 eV–0.5 eV. Reasonable agreement is found in the comparison between present results and previous available theoretical results. We carried out statistical analyses with all the trajectories and found two main distinct reaction mechanisms in the collision process, in which the stripping mechanism(i.e., without roaming process) is dominated over the collision energy range. The polarization dependent differential cross sections(PDDCSs) indicate that forward scattering dominates the reaction due to the dominated mechanism. Furthermore,the reactant vibration leads to a reduction of the reactivity because of the barrierless and attractive features of PES and mass combination of the system.