D+CD4→CD3+D2反应的四维量子散射计算

运用约化维数量子动力学理论 ,利用含时波包法 ,对反应D +CD4 →CD3+D2 进行了四维量子散射计算 .将反应多原子CD4 看作双原子D—CD3,反应D +CD4 →CD3+D2 看作单原子 双原子反应 ,把体系的反应简化为四维散射问题 .波函数的传播采用分裂算符法 ,为避免格点边界处含时波函数的边界反射 ,采用了光学吸收势法 ,在格点边界处引入光学势 ,消除边界反射 .根据CD4 分子的C3v对称性 ,选取了Jordan和Gilbert提出的半经验势能面 .计算结果表明 ,反应概率随平动能的变化图像 ,呈现出显著的量子共振特性 ,这是很多提取反应的共同特征 .而不同振动态下的反应概率随平动能的变化表明 ,随振动量子数的增大 ,反应概率有明显提高 ,且反应阈能明显降低 ,这说明反应分子的振动能对分子的碰撞反应有重要贡献 .而对基态和第一振动激发态时散射截面的计算 ,也证明了这一结论 .同时 ,还分别通过计算量子数j,k ,m对反应概率的影响 ,对该反应的空间取向效应进行了研究 ,并与H +CH4→CH3+H2 反应进行了比较 .     

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.     

BF分子A1Π→X1Σ+带系与b3Σ+→a3Π带系的Franck-Condon因子计算

在双原子分子核运动的波动方程中，计入分子的振转相互作用项，得出的波函数除与振动量子数有关外，还与转动量子数有关．用该波函数编程序计算了BF分子A¹Π→X¹Σ⁺带系和b³Σ⁺→a³Π带系的Franck-Condon因子．计算中转动量子数的取值由J=0取至J=200，结果适用于低温、高温和强激波条件． 关键词：     

不同能量的氦原子与同位素分子H2(D2，T2)碰撞分波截面的理论计算

用Tang-Toennies势模型和密耦近似方法计算了不同能量下惰性气体原子He与H₂及其同位素D₂，T₂替代碰撞体系的振转激发碰撞截面. 通过分析He-H₂(D₂，T₂)各碰撞体系分波截面的差异，总结出在H₂分子的对称同位素替代情形下He-H₂(D₂，T₂)碰撞体系分波截面随量子数和体系 关键词： 散射截面 密耦方法 同位素     

Ar-D2O复合物在D2O弯曲振动模附近的新振转子带

稀有气体原子和水分子组成的范德瓦耳斯复合物是研究水和其他原子分子之间相互作用的典型模型.本文利用中红外连续外腔量子级联激光器结合脉冲超声分子束吸收光谱技术,在D₂O弯曲振动带(v₂=1←0)附近测量了Ar-D₂O复合物4个新的振动转动子带.基于赝双原子分子有效哈密顿量,本文对测量到的振动转动谱线和前人报道的下能级所涉及的纯转动谱线进行了最小二乘法全局拟合,得到了包括振动子能级能量、转动常数和离心畸变常数等在内的精确的基态和激发态分子参数.Ar-D₂O的D₂O弯曲振动激发的振动带头被精确确定为1177.92144 (32) cm^-1,该值比D₂O单体的带头红移了约0.458 cm^-1.将从实验得到的振动子能级能量与基于四维势能面的理论计算结果进行了比较,检验了理论计算方法的精度.     

CH3I分子的光解离的自旋-轨道从头计算

采用从头计算二阶自旋-轨道多组态准简并微扰理论计算了碘代甲烷CH₃I分子与基态²I⁰_3/2和激发态²I^0*_1/2原子解离极限相关联的势能曲线. 计算了CH₃I分子的吸收谱，分析了CH₃I分子的光解离过程，并估计了激发态碘原子²I^0*_3/2的量子产额. 计算结果表明，该方法可用以解释光解离实验结果. 关键词： 3I分子')" href="#">CH₃I分子 自旋-轨道耦合 量子产额 光解离     

激光诱导荧光法研究CH2Cl2分子的振动能量转移

本文中用激光诱导荧光法首次研究了有机分子CH₂Cl₂分子的振动能量转移。实验测得了CH₂Cl₂分子的ν₃和ν₃/ν₉振动模的激活和消激活速率常数,以及稀有气体分子对CH₂Cl₂分子的ν₃/ν₉振动模消激活的影响。用SSH理论计算了CH₂Cl₂-稀有气体碰撞,CH₂Cl₂分子ν₃/ν₉的V-T能量转移相对几率,分析讨论了CH₂Cl₂分子的振动能量转移的通道。 关键词：     

C42+的几何构型和Jahn Teller效应

用从头计算法QCISD/6-311G得到了C₄²⁺分子的10种不同的几何构型,其中包括C_s,C_∞v,C_2v,D_2h,D_∞h,D_4h,D_2d,C_3v等不同的构型.计算表明C₄²⁺的T_d构型不能稳定存在,详细讨论了T_{d 关键词： 几何构型 4}²⁺')" href="#">C₄²⁺ Jahn Teller效应     

低能电子与氢分子碰撞的振动激发积分散射截面的研究

采用振动密耦合方法,研究了低能电子与H₂分子碰撞的振动激发积分散射截面.研究表明,使用18个Morse振动波函数、5个分波和4个对称性可以得到收敛的0→0,0→1,0→2和0→3积分散射截面;而且振动波函数的性质和振动能级的精确性会直接影响振动激发散射势能和振动激发积分散射截面.计算结果与实验符合得很好. 关键词： 电子散射 振动激发 2分子')" href="#">H₂分子 积分截面     

以Ne原子为联合原子的系列分子里德伯能级结构

本文在独立电子近似的基础上,利用多重散射自洽场理论方法,系统地计算了含10个电子的分子B₂,HF,H₂O,NH₃,CH₄的里德伯能级结构,通过分析这些分子量子数亏损的变化规律,阐明了其激发态的电子能级结构,根据分子电子组态的联合原子极限,确定了各里德伯初始态的主量子数,量子数亏损的计算值与已有的实验值符合良好。 关键词：     

Time-dependent quantum dynamics study for reaction of D+CH4→CH3+HD

The semirigid vibrating rotor target (SVRT) model has been applied to the study of the reaction of D+CH_4→CH_3+HD using a time-dependent wave packet method. The energy dependence of the calculated reaction probability shows oscillatory structures similar to those observed in the abstraction reaction of H+H_2, H+CH_4 etc. We have also studied the influence of rotational and vibrational excitation of the reacting molecule (CH_4) on reaction probability. The excitation of the H－CH_3 stretching vibration gives significant enhancement of reaction probability, which rises significantly with the enhancement of rotational quantum number j. Finally, we have compared the cross section and the rate constant of the D+CH_4 system with that of the H+CH_4 system.     

D+CD4→CD3+D2反应的量子含时动力学研究

运用半刚体振动转子靶(semirigid vibrating rotor target)模型,利用含时波包法(TDWP method),对反应D+CD4→CD3+D2进行了量子含时动力学研究与计算.反应几率随平动能的变化图象,呈现出显著的量子共振特性.并通过对v=0时,j=0,1,2的反应几率以及j=0时,v=0,1的反应几率的计算,对该反应的空间效应进行了研究与分析.     

Vibrational and rotational excitation effects of the N(2D) + D2(X1Σg +) → ND(X3Σ+) + D(2S) reaction

The effects of the rovibrational excitation of reactants in the N(²D) + D₂(X¹Σ_g⁺) → ND(X³Σ⁺) + D(²S) reaction are calculated in a collision energy range from the threshold to 1.0 eV using the time-dependent wave packet approach and a second-order split operator. The reaction probability, integral cross-section, differential cross-section and rate constant of the title reaction are calculated. The integral cross-section and rate constant of the initial states v = 0, j = 0, 1, are in good agreement with experimental data available in the literature. The rotational excitation of the D₂ molecule has little effect on reaction probability, integral cross-section and the rate constant, but it increased the sideways and forward scattering signals. The vibrational excitation of the D₂ molecule reduced the threshold and broke up the forward–backward symmetry of the differential cross-section; it also increased the forward scattering signals. This may be because the vibrational excitation of the D₂ molecule reduced the lifetime of the intermediate complex.     

Direct ab initio molecular dynamics study of F atom reaction with methane

The dynamics of the F + CH₄ → HF + CH₃ and F + CD₄ → DF + CD₃ reactions have been investigated using classical trajectory calculations at the MP2/cc-pvdz level of theory. The trajectories were calculated directly from electronic structure computations, and a Hessian based method with updating was used to integrate the trajectories. Using this method, product rovibrational populations and internal energy distributions were obtained for the F + CH₄ and F + CD₄ reactions. The theoretical results were compared with the available experimental data and previous calculations results. The state distributions of the reaction F + CH₄ in these calculations are in reasonable agreement with the experimental results, which indicates that the experimental behavior of the reaction could be well reproduced by the direct classical trajectory calculations at MP2/cc-pvdz level. As such, the product rovibrational populations and internal energy distributions for the reaction F + CD₄ were predicted. The same degree of agreement between theory and experiment as the F + CH₄ reaction is expected.     

Semirigid vibrating rotor target calculation for reaction O(<Superscript>3</Superscript>P)+CH<Subscript>4</Subscript>→CH<Subscript>3</Subscript>+OH

The time-dependent quantum dynamics calculation for reaction O(³P)+CH₄ →CH₃+OH is made, using of the semirigid vibrating rotor target (SVRT) model and the time-dependent wave packet (TDWP) method. The corresponding reaction probabilities of different initial states are provided. From the calculation of initial rovibrational statej=0,v=0, 1, we can see that the excitation of the H-CH₃ stretching vibration gives significant enhancement of reaction probability and the reaction threshold decreases dramatically with the enhancement of the vibrating excitation, which indicates that the vibrating energy of reagent molecules contributes a lot to the molecular collision. As for the calculation of reaction probability of statev=0,j=0,1,2,3, the results show that the reaction probability rises significantly with the enhancement of rotational quantum numberj while the reaction threshold has no changes. The spatial steric effect of the title reaction is studied and analyzed too after the calculation of reaction probability of statesj=5,k=0–2,n=0 andj=5,k=2,n=0–2 is made.     

Rotational relaxation of symmetric tops CH3D and CD3H in some inert liquids

Infra-red spectra of CH₃D and CD₃H dissolved in liquid Ar, Kr, Xe, N₂, O₂ and CH₄ or CF₄ have been recorded. From the band shapes, rotational correlation functions, band moments and intermolecular mean square torques have been calculated. To describe the tumbling motion, involved in the parallel band profiles, we have computed the theoretical correlation functions in the m or j diffusion limits. The validity of these Gordon models is discussed. In an attempt to obtain some information on the rotational diffusion tensor, experimental correlation times have been estimated from A₁ and E bands of CD₃H.     

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.     

O(1D)和CD4反应的准经典轨线

在新的全域势能面上, 用准经典轨线方法细致地研究了O(¹D)+CD₄多通道化学反应的动力学．这个势能面是用交换不变多项式方法基于MRC+Q/aug-cc-pVTZ从头算点拟合得到的．通过计算得到了产物OD+CD₃、D+CD₂OD/CD₃O和D₂+DCOD/D₂CO的分支比、平动能分布以及角度分布,结果显示理论与实验吻合得较好, 从而说明了这个反应的同位素取代效应很小． 研究表明,O(¹D)+CD₄反应是经过陷入的抽取机理发生的： 最初主要通过D原子的抽取,并不是之前人们认为的直接C-D键的插入形成CD3OD中间物后再进而解离成各个产物通道．     

Infrared spectroscopic studies of partially deuterated ethanes and the r0, rz, and re structures

Samples of CH₃CH₂D, CH₃CHD₂, CD₃CH₂D, and CD₃CHD₂ have been prepared, and their infrared spectra recorded. Analysis of type B or type C “perpendicular” bands has enabled the rotational parameter ($\text{A}{}_0\text{-}\text{B}{}_0$) to be determined for all four species. These have been combined with existing infrared, Raman, and microwave data for CH₃CH₃, CD₃CD₃, and CH₃CD₃ species, to determine the ground state (r₀) and ground state average (r_z) structures within narrow limits. Zero point energy effects on the average structure are determined to be a CH bond shortening of 0.0015(3) Å and an HCC angle opening of 0.010(5)° on deuteration. These effects enable the equilibrium structure of ethane to be estimated. The r_z(CC) bond length is determined to be 1.5351(2) Å, which is significantly longer than previous estimates involving electron diffraction data.     

Hydrogen-bonded OH and OD overtone bands and potential energy curve of methanol

The absorption spectra of CH₃OH, CH₃OD, CD₃OH, and CD₃OD as pure liquids and as carbon tetrachloride solutions were measured in the 3,850 – 16,600cm^?1 region. In addition to the various combination bands, the higher overtone bands of the hydrogen-bonded OH stretching vibration of self-associated methanols were observed at ～6470, 9300–9700, and 12,200 – 12,700 cm^?1 with broad half-widths of ～700, ～1200, and ～1800 cm^?1, respectively, and those of the OD stretching vibration, at ～4900, 7200–7400, and 9200–9600 cm^?1 with half-widths of ～370, ～700, and ～1200 cm^?1, respectively. With the aid of the observed frequencies, we determined the single minimum potential energy curve for the hydrogen-bonded OH and OD stretching vibrations of self-associated methanols. Furthermore, the absorption band due to double excitation of two neighboring OH groups linked together by a hydrogen bond was quantitatively analyzed by using the isotopic isolation technique. The double excitation band of CH₃OH as pure liquid was found to appear at 6730 cm^?1 with an absorbance of 0.08 at 1 mm light path length.