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 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.     

He+H2+ HeH++H反应的从头算势能面"

运用多参考组态相互作用（MRCI）方法及aug-cc-pv5z基组构造了HeH2+体系基态（1 ）从头算势能面。采用多体展开法共拟合了8840个能量点,拟合误差为0.0677Kcal/mol。基于新势能面,采用准经典轨线方法计算了碰撞能在0-2 eV范围内的积分反应截面,计算结果与实验结果符合较好。     

O(1D)+N2O→NO+NO反应的理论研究

应用三体模型及扩展的LEPS势能面(PES),对初始条件为(Ecol=55 kJ/mol,v=0,j=0)的O(1D)+N2O→NO+NO反应体系进行了准经典轨线(QCT)计算.根据计算结果对体系的势能面及反应机理进行详细的分析和讨论,较全面地研究了此反应体系的动力学特征.     

Theoretical study of stereodynamics for the reaction O(3P) +D2 (v=0, j=0) to 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(θ_r) and P(ø_r) 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(θ_r) and PDDCSs of the ³A′ PES while the opposite on P(ø_r) of the ³A″ potential energy surface.     

O~+ + H_2及其同位素取代反应的立体动力学研究

运用准经典轨线方法,基于RODRIGO势能面,对碰撞能为20kcal/mol时,O++H2及其同位素取代反应的立体动力学性质进行了理论研究,对k-j′两矢量相关和k-k′-j′三矢量相关的分布函数、极化微分反应截面,以及产物转动取向参数进行了详细的讨论.结果表明,O++H2→OH++H,O++DH→OD++H和O++TH→OT++H反应的立体动力学性质对体系的质量因数非常敏感.     

Insertion and abstraction pathways in the reaction O(1D2) + H2-->OH+H

Rigorous quantum dynamical calculations have been performed on the ground 1 1A' and first excited 1 1A" electronic states of the title reaction, employing the most accurate potential energy surfaces available. Product rovibrational quantum state populations and rotational angular momentum alignment parameters are reported, and are compared with new experimental, and quasiclassical trajectory calculated results. The quantum calculations agree quantitatively with experiment, and reveal unequivocally that the 1 1A" excited state participates in the reaction.     

Quantum mechanical studies on the singlet and triplet potential energy surface of the reactions CF3O2 + I,CF3O + OI and CF3 + OIO

The singlet and triplet potential energy surfaces for the reactions CF₃O₂ + I (1), CF₃O + OI (2) and CF₃ + OIO (3) are investigated using ab initio quantum mechanical methods. Four important isomeric energy minima were found, three on the singlet surface, CF₃OOI, CF₃OIO and CF₃IO₂ and one on the triplet surface ³CF₃OIO. CF₂O + FOI are shown to be the most probable products for all reactions, CF₃O +I and CF₃O + O(³P) are possible for reactions (2) and (3) while the reaction pathway leading to CF₃O +OI is also possible for reaction (3).     

H/D/T+LiH反应的立体动力学研究

利用准经典轨线方法,在Prudente 等人发表的LiH2体系势能面[Chem. Phys. Lett. 474, 18 (2009)]上研究了原子分子反应H/D/T+LiH →HH/HD/HT+Li的立体动力学性质。在不同碰撞能下分别计算了该反应的反应截面,以及碰撞能为0.25eV时的微分反应截面、角分布P(θr)。计算结果表明,随着碰撞能和攻击原子质量的增加,反应截面逐渐减小。对于所选定的碰撞能,当攻击原子质量增加时,反应产物向前散射趋势增强,向后散射的趋势几乎保持不变,产物的转动角动量j′取向程度增强并且定向于y轴负方向。     

Isomers of OCS and their reaction with H2O on singlet potential energy surface

The isomers of the carbonyl sulfide (OCS) molecule are investigated in detail at CCSD(T)/cc-pVTZ//MP2/6-311++G(2d,2p) level of theory. One cyclic isomer was identified along with three different linear minima of the OCS molecule. Three interconversion transition states were also located between cyclic and linear forms of OCS. Among these four isomers, the singlet potential energy surface (PES) for the molecule–molecule reaction between the three most energetically favoured isomers of OCS and H₂O has been explored theoretically at the CCSD(T)/cc-pVTZ//MP2/6-311++G(2d,2p) level. This singlet PES comprises of three paths. Path 1 is the reaction of linear OCS molecule with water producing the major product P1 (CO₂?+?H₂S), minor product P2 (S?+?HCOOH) and two isomers via 14 minima and 15 transition states. The Path 2 is an isomerization process in which cyclic isomer of OCS reacts with water molecule via another initial barrierless aduct producing five isomers of the OCS–H₂O system through five interconversion transition states. The reaction of linear COS isomer with water is shown in Path 3. This path produces the radicals SH and COOH from another COS–H₂O complex via a transition state. Among these three products, the product P1 is energetically most favoured. The overall exothermicity of the product channels for the formation of major product P1 on PES is calculated to be about 10.60?kcal/mol possessing initial high entrance barriers of 45.48 and 55.47?kcal/mol in two possible pathways. As the process is favoured thermodynamically but not kinetically, the reaction is expected to be very slow.     

Chern-Simons correlations on (2+1)D lattice

The contribution of zero modes to the value of the number of particles in a discrete model of the (2+1)-dimensional nonlinear Schrödinger equation is computed. It is shown for the first time that in the region of small values of the Chern-Simons coefficient k there exists a universal attraction between field configurations. For k=2 this phenomenon may be a dynamic origin of the semion pairing in the high-temperature superconducting state of planar systems. The preliminary results of this paper were presented in the proceedings of the XI International Conference on Problems of Quantum Field Theory (Dubna, 13–17 July 1998).     

Theoretical study of stereodynamics for the N+H2/D2/T2 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.     

F+H2化学反应中的Feshbach共振之研究

化学反应共振态研究是化学动力学研究的重要前沿课题,对于理解基元化学反应的机理有重要的意义.本文中介绍了最近在这一研究方向的重大进展.通过对F+H2化学反应的全量子态分辨的分子束反应散射实验研究,观测到了F+H2中反应中明显的反应共振现象.通过高精度的全量子散射动力学研究,发现这一共振现象是由两个Feshbach共振态所引起的,而且这两个Feshbach共振态之间在前向散射有明显的量子干涉效应.这项研究工作使得我们对这一重要基元反应中的化学反应共振态研究向前迈进了一大步.     

F+H2化学反应中的Feshbach共振之研究

化学反应共振态研究是化学动力学研究的重要前沿课题,对于理解基元化学反应的机理有重要的意义.本文中介绍了最近在这一研究方向的重大进展.通过对F＋H2化学反应的全量子态分辨的分子束反应散射实验研究,观测到了F＋H2中反应中明显的反应共振现象.通过高精度的全量子散射动力学研究,发现这一共振现象是由两个Feshbach共振态所引起的,而且这两个Feshbach共振态之间在前向散射有明显的量子干涉效应.这项研究工作使得我们对这一重要基元反应中的化学反应共振态研究向前迈进了一大步。     

Kinematics of the reaction H2O+(H2,H)H3O+

The kinematics of the reaction H₂O⁺(H₂,H)H₃O⁺ were studied in crossed-beam experiments in the low collision-energy range 0.1–2 eV (c.m.). The scattering diagrams, center-of-mass angular distributions, and product relative translational energy distributions obtained show that the reaction proceeds predominantly by the impulsive, stripping mechanism. The translational exoergicity vs. collision energy plot obeys the spectator-stripping prediction.     

Dependence on collision energy of the stereodynamical properties of the 18O + 32O2 exchange reaction

We report a quantum stereodynamical study of the ¹⁸O + ¹⁶O¹⁶O(v = 0, j = 1) → ¹⁸O¹⁶O(v′ = 0, j′) + ¹⁶O oxygen exchange reaction at four different collision energies. We calculated the polarisation moments and generated stereodynamical portraits related to the key vectors involved in this collision process. Ozone complex-forming approaches of reactants are then deduced. The results indicate that different approaches are possible but strongly depend on the collision energy and other parameters of the collision. We also conclude that the reaction globally tends to favour a perpendicular approach with increasing energy.     

基于4A"势能面研究C(3P)+NO(X2Π)→CO(X1Σ+)+N(4S)反应的立体动力学性质

运用准经典轨线方法(QCT), 基于Abrahamsson等构造的⁴A"势能面(Abrahamsson E Andersson S, Nyman G, Markovic N 2008 Phys. Chem. Chem. Phys. 10 4400), 在碰撞能为0.06 eV时, 对C(³P)+NO(X²Π )→CO(X¹Σ⁺)+N(⁴S)反应立体动力学性质进行了理论研究. 在考虑反应物NO转动和振动激发的条件下, 计算了质心坐标系下k-j'矢量(k与j'分别为反应物速度与产物角动量)相关的P(θ_r)分布和k-k'-j'矢量(k'为产物相对速度)相关的P(φ_r)分布. 此外还计算了该反应的三个极化微分截面(2π/σ)(dσ₀₀/dω_t), (2π/σ)(dσ₂₀/dω_t)以及(2π/σ)(dσ₂₂+dω_t). 计算结果表明转动和振动激发对产物取向影响较大而对定向影响较小; 对于三个极化微分截面, 转动激发的影响不大, 而振动激发的影响则较大.     

振动激发对H+CH反应矢量性质的影响

基于从头算势能面CH2 ,用准经典轨线(QCT)方法研究了不同振动激发(v=0-3)下反应H+CH→H2+C(1D)的动力学性质．在质心坐标系下计算了四个极化微分反应截面(PDDCDs),计算并讨论了描述 k- j''矢量相关的 分布函数和描述k- k-'' j''三矢量相关的二面角分布 。研究结果表明势能面上的深势阱和不同的振动态对产物分子H2有重要影响。     

振动激发对H+CH反应矢量性质的影响

基于从头算势能面CH2(1A'),用准经典轨线(QCT)方法研究了不同振动激发(v=0-3)下反应H+CH→H2+C(1D)的动力学性质.在质心坐标系下计算了四个极化微分反应截面(PDDCDs),计算并讨论了描述k-j'矢量相关的P(θr)分布函数和描述k-k-'j'三矢量相关的二面角分布P(φr).研究结果表明势能面上的深势阱和不同的振动态对产物分子H2有重要影响.