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.     

State-to-state dynamics of reactions H+DH'(v=0,j=0)→HH'(v',j')+D/HD(v',j')+H'with time-dependent quantum wave packet method

State-to-state time-dependent quantum dynamics calculations have been carried out to study H+DH'→HH'+D/HD+H' reactions on BKMP2 surface.The total integral cross sections of both reactions are in good agreement with earlier theoretical and experimental results,moreover the rotational state-resolved reaction cross sections of H+DH'→HH‘+D at collision energy Ec=0.5 eV are closer to the experimental values than the ones calculated by Chao et al [J.Chem.Phys.117 8341(2002)],which proves the higher precision of the quantum calculation in this work.In addition,the state-to-state dynamics of H+DH'→ HD'+H reaction channel have been discussed in detail,and the differences of the micro-mechanism of the two reaction channels have been revealed and analyzed clearly.     

Quasi-classical trajectory study of the isotope effect on the stereodynamics in the reaction H(2S)+CH(X2Π; v=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(θ_r), P(ø_r), P(θ_r, ø_r), 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 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.     

Influence of rotational excitation and collision energy on the stereo dynamics of the reaction： N（4S）＋H2 （v = 0, j = 0, 2, 5, 10） →NH（X3∑-）＋H

The N+H₂ reaction has attracted a great deal of attention from both the experimental and the theoretical community, and most of the attention has been paid to the first excited state N(²D) atoms in collisions with hydrogen molecules and the scalar properties of the reaction. In this paper, we study the stereo dynamical properties and calculate the reaction cross sections of the N(⁴S) + H₂ (v=0, j=0, 2, 5, 10) → NH(X³Σ^-) + H using the quasi-classical trajectory (QCT) method on an accurate NH₂ potential energy surface (PES) reported by Poveda and Varandas [Poveda L A and Varandas A J C 2005 Phys. Chem. Chem. Phys. 7 2867], in a collision energy range of 25 kcal·mol^-1-140 kcal·mol^-1. Results indicate that the reactant rotational excitation and initial collision energy both have a considerable influence on the distributions of the k-j′ correlation, the k-k′-j′ correlation and k-k′ correlation. The differential cross section is found to be sensitive to collision energy.     

State-to-state quantum dynamics of the N(~4S)+H_2(X~1Σ~+) → NH(X~3Σ~-)+H(~2S) reaction and its reaction mechanism analysis

Quantum state-to-state dynamics of the N(4S) + H-2(X1+Σ) → NH(X3Σ) + H(2S) reaction is reported in an accurate novel potential energy surface constructed by Zhai et al.(2011 J. Chem. Phys. 135 104314). The time-dependent wave packet method, which is implemented on graphics processing units, is used to calculate the differential cross sections. The influences of the collision energy on the product state-resolved integral cross sections and total differential cross sections are calculated and discussed. It is found that the products NH are predominated by the backward scattering due to the small impact parameter collisions, with only minor components being forward and sideways scattered, and have an inverted rotational distribution and no inversion in vibrational distributions; both rebound and stripping mechanisms exist in the case of high collision energies.     

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.     

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.     

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

Quasiclassical trajectory (QCT) calculations have been performed for the abstraction reaction, D' +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(θ_r), P(φ_r), and P(θ_r,φ_r), together with the four commonly used polarization-dependent differential cross sections ((2π/σ)(ds₀₀/dω_t), (2π/σ)(ds₂₀/dω_t), (2π/σ)(ds₂₂₊/dω_t), (2π/σ)(ds_21-/dω_t)) 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.     

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) $({2\pi } / \sigma )(\d\sigma _{00} / \d\omega _t )$, $({2\pi } / \sigma )(\d\sigma _{20} / \d\omega _t )$, $({2\pi } / \sigma )(\d\sigma _{22 + } / \d\omega _t )$, and $({2\pi } / \sigma )(\d\sigma _{21 - } / \d\omega _t )$ are calculated in the centre-of-mass frame. The distribution of the angle between ${{\bm k}}$ and ${{\bm j^\prime }}$, $P(\theta _r )$, the distribution of the dihedral angle denoting ${{\bm k}}${--}$\bm k^\prime $--$\bm j^\prime $ correlation, $P(\phi _r )$, as well as the angular distribution of product rotational vectors in the form of polar plots $P(\theta _r ,\phi _r )$ are calculated. The isotope effect is also revealed and primarily attributed to the difference in mass factor between the two title reactions.     

碰撞能对S(1D) +H2(v=0, j=0)→SH+H反应立体动力学性质的影响

利用1A′态的势能面[ Ho et al., J. Chem. Phys. 116, 4124 (2002)],采用准经典轨线方法研究了在不同碰撞能条件下,S(1D) +H2(v=0, j=0)→SH+H反应的立体动力学性质. 通过计算得到了描述反应物速度矢量k与产物的转动角动量矢量j′这两个矢量相关的分布函数P(r)、描述反应物速度矢量k、产物速度矢量k′与产物的转动角动量矢量j′这三个矢量相关的二面角分布函数P(r)以及描述反应产物角动量极化的分布函数P(r,r).计算结果表明产物的转动角动量矢量j′在空间具有明显的定向和取向效应,并且产物的转动角动量具有强烈的极化. 另外,计算结果还表明这些立体动力学性质对碰撞能非常敏感.     

碰撞能对S(1D) +H2(v=0, j=0)→SH+H反应立体动力学性质的影响

利用1A′态的势能面[ Ho et al., J. Chem. Phys. 116, 4124 (2002)],采用准经典轨线方法研究了在不同碰撞能条件下,S(1D) +H2(v=0, j=0)→SH+H反应的立体动力学性质. 通过计算得到了描述反应物速度矢量k与产物的转动角动量矢量j′这两个矢量相关的分布函数P(r)、描述反应物速度矢量k、产物速度矢量k′与产物的转动角动量矢量j′这三个矢量相关的二面角分布函数P(r)以及描述反应产物角动量极化的分布函数P(r,r).计算结果表明产物的转动角动量矢量j′在空间具有明显的定向和取向效应,并且产物的转动角动量具有强烈的极化. 另外,计算结果还表明这些立体动力学性质对碰撞能非常敏感.     

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, D'+ DS(v = 0, j = 0) → D'D + S on a new LZHH potential energy surface (PES) of the adiabatic 3 A 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 ((2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt), (2π/σ)(dσ21/dωt)) 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.     

The effect of the rotational excitation of NO on the stereodynamics for the reaction C(~3P)+NO(X~2Π)→CN(X~2Σ~+)+O(~3P)

The stereodynamic properties of the reaction C(3P)+NO(X2Π)→CN(X2Σ+)+O(3P) in different rotational states of reactant NO are studied theoretically by using the quasiclassical trajectory method on 2A' and 2A' potential energy surfaces(PESs) at a collision energy of 0.06 eV.The vector properties in different rotational states on the two surfaces are discussed in detail.The results indicate that the rotational excitation of NO has considerable influence on the stereodynamic property of the reaction occurring on the two surfaces.At the same time,the calculated polarization-dependent differential cross sections(PDDCSs) in different initial rotational states manifest that products are strongly polarized at three scattering angles.     

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.     

Theoretical Studies of O(1D)+HD (v=0, j=0, 1, 2, 3)→OD(H)+H(D) Reaction

利用准经典轨线计算方法在DK势能面上对O+HD进行了计算,获得了产物的反应截面和分支比OD/OH. 计算结果表明,当碰撞能由4.6 kJ/mol增加到46.0 kJ/mol时,产物的反应截面随着碰撞能的增加明显减小;产物的平均分支比随着转动量子数的增加逐渐减小.     

Quantum and quasiclassical dynamics of C(3P)+H2(1∑+g)→ H(2S)+CH(2Π)reaction:Coriolis coupling effects and stereodynamics

The dynamics of C+H2 → H+CH reaction is theoretically studied using the quasiclassical trajectory and quantum mechanical wave packet methods.The analysis of rea...     

The effect of surface temperature on H2/D2(v = 0, j = 0)–Ni(100) scattering processes

We carry out both four-dimensional (4D×2D) and six-dimensional (6D) quantum dynamics on a parametrically time- and temperature-dependent effective Hamiltonian for H₂/D₂(v = 0,j = 0)–Ni(100) collision process. Such an effective potential was derived within a theoretical framework of mean-field approximation by considering weakly correlated interaction between molecular degrees of freedom, phonon modes and electron– hole pair (elhp) coupling through a Hartree-product-type wave function, where the initial state distribution of the surface modes and elhp coupling were introduced through Bose– Einstein and Fermi– Dirac probability factor, respectively. The temperature-dependent dissociation and state-to-state transition probabilities for H₂/D₂(v = 0,j = 0)–Ni(100) system are depicted as a function of initial kinetic energ of the incoming diatom. Though such effect appears negligibly small for H₂(v = 0,j = 0)–Ni(100) system, it is prominent in the case of D₂(v = 0,j = 0)–Ni(100) collision. It appears that the change of dissociation and transition probabilities of D₂ with the increase of surface temperature is exclusively dictated by the phonon modes directed along Z-axis, but the effect of elhp coupling particularly for transition probabilities is insignificant.     

State-specific rotational energy transfer in OH (A 2Σ+, v′=0) by some combustion-relevant collision partners

State-to-state rotational energy transfer (RET) co-efficients were determined for inelastic collisions of OH (A ²⁺, v=0) with N₂, CO₂, and H₂O at 300 K. The experimental procedure described previously allows the direct evaluation of state-specific RET coefficients from time-resolved laser-induced fluorescence (LIF) measurements without any assumptions on the RET. The results show strikingly different RET behaviour for the three collision partners. The data can serve as a basis for a comparison with dynamic collision models.A. Jörg is now with IBM Corporation, Frankfurt, Fed. Rep. Germany