C1与C3D6H2和C3H6D2反应的立体动力学对比研究

在扩展的London-Eyring-Polanyi-Sato（LEPS）势能面上，利用准经典轨线法研究了碰撞能为Ecol=6．0kcal／mol时C1与C3D6H2和C3H6D2反应．在质心系中计算了极化微分反应截（2π／σ）（dσ00／dωt）、两矢量相关的P（θr）分布、三矢量相关的极角分布P（Ф）以及用θr和Фr表示的产物转动角动量的空间分布，计算结果与有关实验及理论结果符合得很好．通过对比研究C1与C3D6H2、C3H6功和C3H8在不同碳位上的反应，发现质量因子在此类反应中起着重要的作用．     

氯与甲烷和重氢甲烷反应的矢量相关研究

在扩展的London?Eyring?Polanyi?Sato(LEPS)势能面基础上,利用准经典轨线法在碰撞能Ecol=3.67 kcal/mol下研究了Cl CH4→HCl CH3和Cl CD4→DCl CD3反应,在质心系计算得到四个广义极化微分反应截面((PDDCS)(2π/σ)(dσ00/dωt)、(2π/σ)(dσ20/dωt)、(2π/σ)(dσ22 /dtω)、(2π/σ)(dσ21-/dωt)和k-k′-j′三矢量相关的极角分布p(r)、k-j′两矢量相关的p(rθ)分布以及用θr和r表示的产物转动角动量的空间分布.计算结果与有关实验及理论结果符合得很好,讨论了氯与甲烷和重氢甲烷反应的立体动力学同位素效应.     

氯与甲烷和重氢甲烷反应的矢量相关研究

在扩展的London-Eyring-Polanyi-Sato(LEPS)势能面基础上,利用准经典轨线法在碰撞能Ecol=3.67 kcal/mol下研究了Cl+CH4→HCl+CH3和Cl+CD4→DCl+CD3反应,在质心系计算得到四个广义极化微分反应截面((PDDCS)(2π/σ)(dσ00/dωt)、(2π/σ)(dσ20/dωt)、(2π/σ)(dσ22+/dωt)、(2π/σ)(dσ21-/dωt)和k-k′-j′三矢量相关的极角分布p(фr)、k-j′两矢量相关的p(θr)分布以及用θr和фr表示的产物转动角动量的空间分布.计算结果与有关实验及理论结果符合得很好,讨论了氯与甲烷和重氢甲烷反应的立体动力学同位素效应.     

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.     

Ca+CH_3I→CaI+CH_3反应的矢量相关研究(英文)

本文采用准经典轨线方法,在LEPS势基础上计算了Ca+CH3I→CaI+CH3在不同碰撞能下的矢量相关计算了质心系中四个广义极化微分反应截面(2π/σ)(dσ00/dωt),(2π/σ)(dσ20/dωt),(2π/σ)(dσ22+/dωt),(2π/σ)(dσ21-/dωt),k-j′两矢量相关的P(θr)分布、k-k′-j′三矢量相关的极角分布P(φr)以及用θr和φr表示的产物转动角动量的空间分布P(θr,φr).     

同位素取代和碰撞能对N（4S）＋H2反应立体动力学性质的影响

基于Poveda等计算得到的DMBE势能面,运用准经典轨线的方法研究了同位素取代和碰撞能对N（4S）＋H2反应的立体动力学性质的影响．计算并讨论了两矢量k-J’相关分布函数P（θr）,三矢量k—k＇-j’相关分布函数P（φr）,空间分布函数P（θr,φr）,微分反应截面和积分反应截面．研究了碰撞能从25kcal/mol到80kcal/mol变化对三个反应N＋H2,N＋D2和N＋T2的影响．结果表明：分子间同位素和碰撞能均会对反应立体动力学性质产生一定的影响．     

采用准经典轨迹的方法研究碰撞能对C+CD→C2+D反应的影响

运用准经典轨线方法,基于¹A'势能面[Mol. Phys. 98, 1925(2000)],从理论上研究了碰撞能对C+CD→C₂+D反应的立体动力学性质的影响．计算并且详细讨论了与产物矢量相关的三个极化分布函数P(θr), P(φr)和P(θr,φr)．此外,在质心坐标系中,研究了碰撞能对两个极化微分反应截面的影响．结果表明,产物C₂的立体动力学性质对反应物分子的碰撞能非常敏感.     

碰撞能对H+HS交换反应立体动力学性质的影响

基于从头算的对称性为1A'的势能面,利用准经典轨线(QCT)方法在不同的碰撞能下研究了交换反应H+HS→HS+H的产物和反应物的矢量相关性质.在质心坐标系下分别计算了反应的描述k-j'矢量相关的P(θr)分布和描述k-k'-j'三者矢量相关的P(φr)分布.同时我们还计算了反应产物的四个极化微分截面.计算结果表明势阱和碰撞能对该反应产物的矢量相关具有重要影响.     

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.     

Ca+RBr→CaBr+R(R=CH3,C2H5,n-C3H7)反应的矢量相关和产物的转动取向

采用准经典轨线方法研究了碰撞反应 Ca RBr(R=CH_3,C_2H_5 和 n-C_3H_7)的矢量相关性质和产物 CaBr 分子的转动取向.计算了不同碰量相关撞能情况下产物分子的转动取向参数和反应物与产物之间的矢分布几率函数.矢量相关由角分布函数 P(θ_r)!P(φ_r)和 P(θ_r,φ_r)以及极化相关微分截面来描述.Ca CH_3Br 反应产物 CaBr 的 P(θ_r)峰值大于 Ca C_2H_5Br 和 Ca n-C_3H_7Br 反应产物 CaBr 的 P(θ_r)峰值.对于反应 Ca RBr 的 P(θ_r)在φ_=3π/2处的峰值明显大于φ_r=π/2处的峰值.计算结果表明,在碰撞反应过程中,产物 CaBr 分子的转动角动量不仅发生取向,而且沿着垂直于散射面方向发生定向：产物 CaBr 分子强烈地沿着反应物相对速度方向向前散射；产物分子转动角动量的定向和取向将不同程度地影响产物的散射方向.     

Variational transition state theory with multidimensional tunnelling and kinetic isotope effects in the reactions of C2H6, C2H5D and C2D6 with .CCl3 to produce CHCl3 and CDCl3

ABSTRACT

Rate constants for the reactions of C₂H₆, C₂H₅D and C₂D₆ with .CCl₃. for the production of CHCl₃ and CDCl₃ (k₁, k₂, k₃ and k₄) were computed using variational transition state theory coupled with hybrid-meta density functional theory (MPWB1K) over the temperature range of 200–2900 K. The ground-state vibrational adiabatic potential was plotted for all channels. Small- and large-curvature tunnelling were determined to include quantum effects in the calculation of rate constants. Harmonic vibrational frequencies along the reaction path were calculated in curvilinear coordinates with scaled frequencies. Anharmonicity was included in the lowest-frequency torsion. The position of formation and dissociation of bonds was specified using the variation in harmonic vibrational frequencies along the reaction path. Representative tunnelling energy and the thermally averaged transmission probability at 298 K (P(E)exp?( ? ΔE/RT)) were determined for the reactions in which tunnelling is important. The kinetic isotope effect was used to calculate the considerable contributions of tunnelling and vibration. The expressions for rate constants were determined using nonlinear least-square fitting over the temperature range of 200–2900 K.     

Infrared intensity analysis of molecules C2H6, C2D6, C2F6 and CF4 zero and first order approximations

Infrared intensity formulae for C₂H₆ and C₂D₆ are derived following the first order approximations. Using the experimental intensities in the intensity equations, the first order coefficients are calculated. They are observed to be negligible compared to the accuracy limits within which the intensities can be measured. Correlating the experimental intensities to the intensity expressions of C₂F₆ and following the zero-order approximations, the bond dipole moment μ and its derivative e are calculated for the C–F bond. Substituting these in the intensity equations of CF₄, transferability of the bond moment parameters is discussed.     

TOTAL CROSSS ECTIONS FOR ELECTRON SCATTERING FROM SIMPLE HYDROCARBON MOLECULES: C_2H_4,C_2H_6 AND C_3H_8

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Comparisons of some molecular properties calculated with basis sets of Slater-type orbitals and floating spherical gaussian orbitals for BH3, BH4 -, B2H6, B4H4, C2H2, C2H4, C2H6, CH4, and C3H4

Some one-electron molecular properties are calculated for BH₃, BH₄ ^-, B₂H₆, B₄H₄, CH₄, C₂H₂, C₂H₄, C₂H₆, and C₃H₄. The wave functions used are constructed from minimal basis sets of STO's and FSGO's. The results obtained from the latter wave functions show that the good agreement with the STO values of the molecular energy is not always maintained with one-electron properties.     

Electronic states of C2H6 +

The complete photoelectron spectrum of ethane has been measured in the valence region using Ne, He I, and He II resonance radiation. The resolution of these spectra is sufficient to partially resolve vibronic structure accompanying the transition to the ground ionic state. The similarity of this structure with that obtained from model calculations using the Jahn-Teller theorem strongly suggests that the active vibration in this transition is a doubly degenerate CH₃ deformation mode and that the ground ionic state is a Jahn-Teller split ² E _g state. These experiments suggest a ² A _1g term for the first excited ionic state. The transition to the ² A _2u state of the ion contains evidence for two active vibrations v ₁ (C–H stretch) and v ₃ (C-C stretch).     

Cavity ring down absorption at low temperatures: C–H spectra (Δυ = 1–6) of CH3D and C–H overtones (Δυ = 5, 6) of CH2D2 and CH4

The spectra of the C–H stretch fundamental and overtones (Δυ = 1–6) of CH₃D have been recorded. Absorptions in the visible were obtained with a phase shift cavity ring down technique where an optical cavity is inside a low temperature cryostat. Absorptions below 12,000 cm^?1 were observed with a Fourier transform spectrophotometer. The local mode harmonic frequency and anharmonicity were obtained and used with the harmonically coupled anharmonic oscillator (HCAO) model to calculate energy levels and assign the absorption bands to particular transitions. Overtone absorptions (Δυ = 5 and 6) of CH₄ and CH₂D₂ have also been obtained. The integrated absorption was calculated as a function of the density of the gas samples and used to obtain the band strength and the cross- section of the Δυ = 5 and 6 C–H transitions for each molecule. Cross–sections for CH₄ agree within 10% with traditional absorption measurements with a multiple pass cell at high pressures. The importance of the new experimental technique is emphasized for laboratory studies of planetary atmospheres.