准经典轨线法研究交换反应H(D)+SH/SD的动力学性质

硫在氢气中的燃烧反应在气象化学、燃烧反应和大气污染中都扮演着重要的角色, 近年来一直受到广泛关注, 其逆反应也渐渐成为人们的研究对象. 以Lü 等得到的精确势能面(Lü S J, Zhang P Y, Han K L, He G Z 2012 J. Chem. Phys. 136 94308) 为基础, 用准经典轨线法对交换反应H(D)+SH/SD的动力学性质进行了研究. 计算了包括反应截面、速率常数、不透明函数、产物振动和转动分布等在内 的标量性质和包括产物散射方向、转动角动量定向和取向性质在内的矢量性质. 详细分析了碰撞能量和同位素效应对反应H(D)+SH/SD 的动力学性质的影响. 结果表明, 随着碰撞能量的增加, 反应截面逐渐增大, 产物的后向散射逐渐减弱, 产物转动角动量的取向和定向性质逐渐增强; 另外, 同位素效应对反应的动力学性质也有明显的影响. 以反应动力学性质和势能面为基础, 详细讨论了反应H(D)+SH/SD 的反应机制. 关键词： 准经典轨线 反应截面 速率常数 振动-转动分布     

Quasi-classical Trajectory Study of the Intramolecular Isotope Effect in the Reaction O(3P)+H2/HD

利用准经典轨线方法在BMS1解析势能面上研究了反应O(³P)+H₂体系的动力学性质. 主要研究了同位素效应对该反应体系的积分截面、产物转动态分布、微分截面、产物角动量的取向和定向以及对极化微分截面的影响. 对于微分截面,还考虑了反应物初始振动量子数对微分截面的影响. 对反应O+HD与O+H₂产生OH的转动发布进行比较,发现前者OH的转动激发更为明显. 微分截面的结果表明,振动量子数和同位素对散射方向有一定影响. 同位素取代对产物的取向和定向以及极化微分截面的影响也比较明显. 对以上结果利用已有的理论模型进行了分析,得到了合理的解释.     

Cl+HD反应产物的极化与态分布

利用准经典轨线理论 ,在BW 2和G3两个势能面上 ,研究了Cl +HD反应的动力学 .计算结果表明 ,产物的转动取向对势能面及反应体系的质量因子非常敏感 .在BW 2势能面上 ,计算的两个产物的转动取向强于在G3势能面上计算的结果 ,而无论是在BW 2势能面上还是在G3势能面上 ,DCl产物的取向都强于HCl产物的取向 .计算结果还表明 ,在不同的势能面上反应物的转动激发对反应的影响有着显著的不同 .在BW 2势能面上 ,反应物的初始转动激发有利于Cl+HD反应的进行 ;而在G3势能面上 ,反应物的初始转动激发消弱了反应的反应性     

反应N(2D)+H2→NH+H和N(2D)+D2→ND+D的立体动力学理论研究.

基于Ho等人的精确势能面(J. Chem. Phys. 119, 3063(2003))研究,运用准经典轨线方法计算了21.3 kJ/mol碰撞能下反应N(²D)+H₂→NH+H和N(²D)+D₂→ND+D的产物与反应物之间的矢量相关．发现两个反应的产物角分布都是前向和后向呈现峰值分布,产物的转动角动量矢量j′不仅是取向的,而且是在y轴负方向上定向的．两个反应显示出的同位素效应主要归因于同位素质量的差别．     

羟基自由基双光子激发解离动力学（英文）

本文利用高里德堡态氢原子飞行时间探测技术,研究了羟基自由基的双光子激发解离动力学.H(~2S)+O(~1D)和H(~2S)+O(~1S)解离通道是山于羟基在经山A~2∑~+(v'=2,J'=0.5-2.5)中间态通过双光子激发最终到排斥性的激发态势能曲线2~2Π和B~2∑~+上产生.这两种解离通道产物都具有各向异性的角向分布,其中H(~2S)+O(~1D)产物角分布异向因子β为-0.97,H(~2S)+O(~1S)产物角分布异向因子β为1.97.各向异性的角向分布与OH自由基在排斥性的激发态势能曲线上直接解离机理相吻合.此实验观测到羟基自山基的解离能为35580±15cm~(-1).     

反应物NO的转动激发对反应N(4S)+NO(X2∏)→N2(X3∑g-)+O(3P)影响的立体动力学研究

采用准经典轨线方法,在碰撞能为0.6 eV时,研究了反应物NO分子的转动激发对发生在3A″和3A′势能面上的反应N(4S)+NO(X2∏)→N2(X3∑g-)+O(3P)的立体动力学性质的影响.详细讨论了在反应物分子的不同转动态下发生在两个势能面上反应的矢量性质.结果表明,反应物分子NO的转动激发对发生在3A′势能面上的立体动力学性质产生重大影响,这可能与该势能面上存在一个早期势垒有关.     

Cl＋HD反应产物的极化与态分析

利用准经典轨线理论，在BW2和G3两个势能面上，研究了Cl+HD反应的动力学。计算结果表明，产物的转动取向对势能面及反应体系的质量因子非常敏感，在BW2势能面上，计算的两个产物的转动取向强于在G3势能面上计算的结果，而无论是在BW2势能面上还是在G3势能面上，DCl产物的取向都强于HCl产物的取向。计算结果还表明，在不同的势能面上反应物的转动激发对反应的影响有着显著的不同。在BW2势能面上，反应物的初始转动激发有利于Cl+HD反应的进行；而在G3势能面上，反应物的初始转动激发消弱了反应的反应性。     

碰撞能和同位素取代对H+BrF→HBr+F反应立体动力学影响的理论研究

基于拟合得到的London-Eyring-Polanyi-Sato势能面,运用准经典轨线方法对H+BrF→HBr+F反应的立体动力学性质进行了理论研究.计算了反映矢量相关的角分布和对光诱导的双分子反应实验敏感的四个极化微分散射截面.结果表明:随着碰撞能的增加,产物的转动极化变强,并且产物的后向散射占主导地位.通过比较D+BrF→DBr+F和H+BrF→HBr+F反应的产物极化,揭示了明显的同位素效应.     

同位素效应对H+NH→N+H2反应的立体动力学性质的影响

基于翟红生和韩克利给出的势能面[Zhai H S, Han K L 2011 J. Chem. Phys. 135 104314], 运用准经典轨线方法对H+NH及其同位素取代反应的立体动力学性质进行了理论研究. 分别计算并讨论了碰撞能E_c=8和16 kcal/mol时反应的极化微分反应截面、两矢量k-j'相关分布函数P(θ_r)、 三矢量 k- k'- j'相关分布函数P(φ_r)、空间分布函数P(θ_r, φ_r). 结果表明, 对于上述的两个碰撞能, 由于同位素取代反应中质量因子的不同, 同位素效应对H+NH反应的立体动力学性质的影响很明显.     

N(4S)+CH3X(X=Cl、Br)反应机理的理论研究

利用abinitio方法对N(4S)+CH3X(X=Cl、Br)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、过渡态和产物的几何构型和谐振频率,在MP2/6311++G(3df,2p)和QCISD(T)/6311+G(d,p)水平上进行单点能计算,并用G2MP2方法计算了所有物种的能量.计算结果表明,反应存在三条反应通道:H抽提反应通道a、Cl或Br抽提反应通道b和替代反应通道c.对于N(4S)+CH3Cl反应,a反应通道是主反应通道,b和c反应通道在反应中有少量贡献.对于N(4S)+CH3Br反应,a反应通道是主反应通道,b和c反应通道在反应中有一定的贡献.     

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.     

H+Li2: 一个典型的释能反应体系及其含时动力学研究

利用含时量子波包动力学理论在HLi₂ 基态势能面上研究了H+Li₂ → LiH+Li 反应的动力学性质. 计算得到了体系在0-0.4 eV 范围内J = 0 不同振动量子数(v = 0, 1, 2, 3), v = 0 不同转动量子数(J = 0, 5, 10,15) 下的反应概率、积分反应截面和热速率常数, 在此基础上讨论了释能反应的反应阈能随总角动量量子数的变化规律以及振动量子数对反应概率的影响等问题. 研究发现, 随着转动量子数的增大, 反应阈能也在逐渐增大; 然而随着振动量子数的增大, 由于反应为释能反应, 反应发生的概率却在逐渐减小. 分析了碰撞能对积分散射截面的影响以及温度对反应速率常数影响的规律.     

State-to-state integral cross sections and rate constants for the N+(3P)+HD→NH+/ND++D/H reaction: Accurate quantum dynamics studies

The reactive collisions of nitrogen ion with hydrogen and its isotopic variations have great significance in the field of astrophysics. Herein, the state-to-state quantum time-dependent wave packet calculations of N$^{+}$($^{3}$P)$+{\rm HD}\to {\rm NH}^{+}$/ND$^{+} +{\rm D/H}$ reaction are carried out based on the recently developed potential energy surface [Phys. Chem. Chem. Phys. 21 22203 (2019)]. The integral cross sections (ICSs) and rate coefficients of both channels are precisely determined at the state-to-state level. The results of total ICSs and rate coefficients present a dramatic preference on the ND$^{+}$ product over the NH$^{+}$ product, conforming to the long-lived complex-forming mechanism. Product state-resolved ICSs indicate that both the product molecules are difficult to excite to higher vibrational states, and the ND$^{+}$ product has a hotter rotational state distribution. Moreover, the integral cross sections and rate coefficients are precisely determined at the state-to-state level and insights are provided about the differences between the two channels. The present results would provide an important reference for the further experimental studies at the finer level for this interstellar chemical reaction. The datasets presented in this paper, including the ICSs and rate coefficients of the two products for the title reaction, are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00034.     

Intrinsic product polarization and branch ratio in the S(~1D,~3P)+HD reaction on three electronic states

The intrinsic product polarization and intramolecular isotope effect of the S(~1D,~3P) + HD reaction have been investigated on both the lowest singlet state(1A) and the triplet state(3A and 3A) potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods.The calculations indicate that intramolecular isotope effects are different on the three electronic states.The stereodynamics study shows that the P(θr) distributions,P(φ r) distributions,and polarization-dependent differential cross sections(PDDCSs)(00) are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.     

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.     

采用量子含时波包方法研究H/D+Li_2→LiH/LiD+Li反应

采用量子波包方法和二阶分裂算符方法对H/D+Li_2→LiH/LiD+Li反应在0.01到0.4 eV的碰撞能范围内进行了动力学计算.在态分辨的理论水平上计算了反应概率、积分截面、微分截面等动力学性质并与之前的理论结果进行了比较.结果表明:由于本文的计算中包含了总角动量J在体固定坐标轴上的所有投影所得,结果更加精确;此外,当H原子被重的同位素原子D取代,反应概率、积分截面增大,然而这并没有对反应机理产生大的影响.前后对称的微分截面表明插入反应机理在反应过程中占据主导地位.     

The stereodynamic properties of the F + HO (v,j)→HF + O reaction on the 1A' and 3A' potential energy surfaces by quasi-classical trajectory: Initial excitation effect (v =1-3, j = 0 and v = 0, j =1-3)

The stereodynamic properties of the F + HO (v, j) reaction are explored by quasi-classical trajectory (QCT) calculations performed on the ¹A' and ³A' potential energy surfaces (PESs). Based on the polarization-dependent differential cross sections (PDDCSs) and the angular distributions of the product angular momentum with the reactant at different values of initial v or j, the results show that the product scattering and product polarization have strong links with initial vibrational-rotational numbers of v and j. The significant manifestation of the normal DCSs is that the forward scattering gradually becomes predominant with the initial vibrational excitation increasing, and the scattering angle of the HF product taking place on the ³A' potential energy surface is found to be more sensitive to the initial value of v. The product orientation and alignment are strongly dependent on the initial rovibrational excitation effect. With enhancement in the initial rovibrational excitation effect, there is an overall decrease in the product orientation as well as in the product alignment either perpendicular to the reagent relative velocity vector k or along the direction of the y axis, for which the initial rotational excitation effect is much more noticeable than the vibrational excitation effect. Moreover, the initial rovibrational excitation effect on the product polarization is more pronounced for the ³A' potential energy surface than for the ¹A' potential energy surface.     

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

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.     

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.