用量子力学方法计算H+H2碰撞的反应几率

利用量子力学耦合通道扭曲波近似法(CCDWA)和三种势能面计算了H+H2碰撞的反应几率,结果发现在相同的势能面下利用CCDWA方法计算的反应几率和公认较好的计算结果符合很好,不同势能面共线势垒高度的差别将引起反应几率的不同.     

Nonadiabatic couplings and charge transfer study in H + CS+ collision using time-dependent quantum dynamics

Experiments have reported the high stability of HCS⁺ ion and inhibit to decompose over the range of collision energies. In this study, the various energy transfer channels of atomic H collision with CS⁺ molecular ion has been performed by ab initio computations at the multireference configuration interaction/aug-cc-pVQZ level of theory. The ground and several low-lying excited electronic state potential energy surfaces in three different molecular orientations, namely, two collinear configurations with, (1) H approaching the S atom (γ = 0°), (2) H approaching the C atom (γ = 180°) and one perpendicular configuration, (3) H approaching the centre of mass of CS (γ = 90°) with the diatom fixed at the equilibrium bond length, have been obtained. Nonadiabatic effects with Landau–Zener coupling leading to avoided crossings are observed between the ground- and the first-excited states in γ = 90° orientation, and also between the first- and second-excited states in γ = 180° orientation. Quantum dynamics have been performed to study the charge transfer using time-dependent wave packet method on the diabatic potential energy surfaces. The probability of charge transfer is found to be highest with 42% in γ = 180°. The high charge transfer probability result in the formation of H⁺ + CS channel which ascertains the high stability of HCS⁺ ion.     

CARS investigations of quenching and photochemical reactions in the Na+H2 collision system

Summary We have carried out parallel studies of the quenching process in Na(3p)+H₂ collisions and the possible reactive process in Na(3p)+H₂ (v ^″=1,2,3) collisions. Rich CARS spectra which were obtained at H₂ pressure of 100 mbar and oven temperature of 600 K indicate the presence of vibrationally excited H₂ and photochemically produced NaH molecules. Temporal resolution of NaH CARS lines was employed in order to rule out competing collisional processes. We make use of resonantly enhanced CARS methods which enabled us to achieve very high sensitivity for NaH detection. Paper presented at the ?XI European CARS Workshop?, Florence, Italy, 23–25 March, 1992.     

Simulation of 12C+12C elastic scattering at high energy by using the Monte Carlo method

The Monte Carlo method is used to simulate the ¹²C+¹²C reaction process. Taking into account the size of the incident ¹²C beam spot and the thickness of the ¹²C target, the distributions of scattered ¹²C on the MWPC and the CsI detectors at a detective distance have been simulated. In order to separate elastic scattering from the inelastic scattering with 4.4 MeV excited energy, we set several variables: the kinetic energy of incident ¹²C, the thickness of the ¹²C target, the ratio of the excited state, the wire spacing of the MWPC, the energy resolution of the CsI detector and the time resolution of the plastic scintillator. From the simulation results, the preliminary establishment of the experiment system can be determined to be that the beam size of the incident ¹²C is φ 5 mm, the incident kinetic energy is 200-400 A MeV, the target thickness is 2 mm, the ratio of the excited state is 20%, the ight distance of scattered ¹²C is 3 m, the energy resolution of the CsI detectors is 1%, the time resolution of the plastic scintillator is 0.5%, and the size of the CsI detectors is 7 cm×7 cm, and we need at least 16 CsI detectors to cover a 0° to 5° angular distribution.     

Observation of OH angular momentum polarization produced by H+O2 at 2.6 eV collision energy

The OH rotational polarization produced by the reaction of fast H atoms from the polarized 193 nm photolysis of HBr with O₂ (2.6 eV collision energy) has been measured by laser-induced fluorescence using polarized analysis light. A strong rotational polarization parallel to the electric vector of the dissociation laser and perpendicular to the flight direction of the H atoms is observed. Implications for the H+O₂ reaction dynamics at high collision energies are discussed.     

气相中Fe+催化CO与N2O循环反应的理论计算研究

采用密度泛函UB3LYP/6–311+G(2d)方法计算研究了Fe+在基态和激发态与CO与N2O反应的反应机理。全参数优化了反应势能面上各驻点的几何构型,用频率分析方法和内禀反应坐标（IRC）方法对过渡态进行了验证,并用UB3LYP/6–311++G(3df,3pd)、单点垂直激发等方法分别进行各驻点单点能校正,四重态和六重态反应势能面交叉点CP确定,计算结果表明,该反应为两步反应,且反应机理都为插入—消去反应,势能面上的两个交叉点能够有效的降低反应的活化能,这在动力学和热力学上都是有利的。     

H+H2反应截面的全量子力学研究

利用全量子力学耦合通道扭曲波近似(CCDWA)方法和三种势能面计算了H+H2(vα=0,jα=0)→H2(vβ,jβ)+H碰撞的反应截面,并与准经典弹道计算结果及公认较好的计算结果作了比较.研究表明:在相同的势能面下利用CCDWA方法得到的截面和公认较好的计算结果符合很好,而准经典弹道计算的反应截面误差较大. 关键词： 反应散射 势能面 反应截面     

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.     

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.     

CH2 CHF与臭氧反应机理的量子化学研究

用量子化学MP2方法 ,在 6 311++G(d ,p)基组水平上研究了烯烃CH2 CHF与臭氧反应的机理 ,对氟代乙烯臭氧化反应Criegee机理进行了系统的计算 ,全参数优化了反应过程中反应物、中间体、过渡态和产物的几何构型 ,在QCISD(T) / 6 311++G(d ,p)水平上计算了它们的能量 .并对它们进行了频率分析 ,以确定中间体和过渡态的真实性 .研究结果表明 ,氟代乙烯与臭氧反应沿Criegee机理是可信的、合理的 .同时研究还发现 ,就氟代乙烯与臭氧反应活性而言 ,其控制步骤的位垒较低 ,可以说氟代乙烯与臭氧反应活性较强 ,也就是说氟代乙烯对臭氧的损耗较大 .     

CoCH2+H2反应机理的密度泛函理论研究

采用密度泛函理论(DFT)中的UB3LYP方法在6-311+G(2d,2p)水平上研究了四重态和二重态的CoCH2与H2反应的机理,在UB3LYP结构优化的基础上用耦合簇理论方法UCCSD(T)在相同水平下对各驻点进行了单点能校正.结果表明,该反应在二重态和四重态上的势能面非常相似,存在两个过渡态(TS1、TS2)和两个中间体(M1、M2),反应的第一步是产生分子复合物(H2)CoCH2,其能量分别比反应物低66.6(四重态)和42.4 kJ/mol(二重态),第二步是H2的加成形成HCoCH3中间体,第三步是CH4的消除反应.其中CH4的消除为整个反应的速控步骤.反应在二重态和四重态势能面上存在四个交叉点,整个反应在二重态势能面和四重态势能面上交替进行.H-H键的活化在四重态上是不可逆的,反应将最终形成四重态产物,整个反应可放出能量222.9kJ/mol.     

H_2CO+OH~-反应的理论研究(英文)

用量化从头算方法在MP4(SDTQ)理论水平上首次考察了甲醛和氢氧根负离子反应的所有可能的反应通道.用6-311 G(3df,3pd)基组对所有的反应中间体、过渡态和产物开展了结构优化和单点能量计算,并经频率分析和内禀反应反应坐标计算(IRC)确认反应物、中间体、过渡态和产物的相关性.在H2CO OH-所有可能的反应通道中生成CHOO- H2的通道是该反应的最可几通道,而由于羰基的存在生成H3O-的通道更容易分解产生CHOO- H2.在高计算水平下计算的氢交换反应结果与文献报道相同.通过计算提出亲核加成过程的反应通道,主要产物生成H2和生成COOH-/HCOO-/OCHO-异构体.所有反应通道的反应几率顺序为COOH- H2>H3O- CO>HCHO OH->CHO- H2O>HCOO- H2>OCHO- H2.     

低碰撞能下H+HF(v=3,j=0)反应的量子动力学研究

报道了H原子和振动激发的HF(v=3,j=0)分子在低碰撞能下的量子反应动力学研究.计算结果表明:在低碰撞能下,散射主要以非反应过程为主;振动激发有利于反应的进行;在小于10-4eV碰撞能下,非反应非弹性散射截面和反应截面的比值约为3.在反应截面上发现了Feshbach共振现象,证实是由反应通道上紧邻反应势垒的H…HF(v=3,j=1～3)的范德瓦尔斯聚合体存在的准束缚态所形成.     

Theoretical study of the reaction of H2 with a Cu2Pt2 cluster

The study of the interaction of a pyramidal tetramer of Cu₂Pt₂ with the H₂ is reported here through ab initio multiconfigurational self-consistent field (MC-SCF) calculations, plus extensive multireference configuration interaction (MR-CI), variational and perturbative calculations. The lowest three electronic states X ¹A′, a ³A′ and a ¹A′ of the bare cluster were considered in order to study this interaction. For the H₂ C_s approaching a Pt vertex, results show that the Cu₂Pt₂ pyramid cluster in its X ¹A′ and a ¹A′ states can spontaneously capture and dissociate the H₂. For the H₂ C_s approaching a Cu vertex, where H₂ is located in the C_s reflecting plane, the Cu₂Pt₂ cluster in its X ¹A′ electronic state shows capture of the hydrogen molecule after surmounting an energy barrier; moreover, in this approach the Cu₂Pt₂ cluster in its a ¹A′ electronic state shows spontaneous capture of the hydrogen molecule. For the H₂ approaching a Cu vertex, where the C_s reflecting plane bisects the H₂ molecule, the Cu₂Pt₂ cluster in its three lowest-lying states is able to capture the hydrogen molecule after surmounting a small barrier. The Cu₂Pt₂+H₂ C_s face-on interactions show a lower H₂ activation than that which was obtained in the equivalent Pt₄+H₂ interactions.     

CH3CH2+O(3P)反应机理的理论研究

利用abinitio方法对CH3CH2+O(3P)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、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6311+G(d,p)水平上进行单点能计算.计算结果表明:CH2O+CH3、CH3CHO+H和CH2CH2+OH是主要反应产物,其中CH2O+CH3主要来自反应通道A1:(R)→IM1→TS3→(A),CH3CHO+H主要来自反应通道B1:(R)→IM1→TS4→(B),CH2CH2+OH主要来自直接抽提反应通道C1和C2:(R)→TS1(TS2)→(C).计算结果同时表明该反应生成CO的通道能垒是非常高的,CO应该不是主要产物.     

A translational energy spectrometer to probe interatomic potentials: Dissociation dynamics of CO2 + ions

A new ion translational energy spectrometer has been developed to carry out low-energy, gas-phase ion-molecule collision experiments which aim to probe molecular potential energy surfaces. The collisional technique employed relates small changes in the kinetic energy of a projectile ion after it has undergone collision with a static neutral atom/molecule to changes in the overall potential energy of the collision system; information can be furnished about the interaction potential between the projectile and the target. First measurements are reported of a high resolution target excitation spectrum obtained in 1.8 keV collisions of H₂ ⁺ ions with N₂. New results pertaining to collision-induced dissociation of CO₂ ⁺ ions are presented and discussed in terms of potential functions of low-lying electronic states of the molecular ion.     

一类有机发色团分子电子吸收跃迁能的计算研究

利用MINDO/3、MNDO、AM1以及PM3四种通用半经验量子化学计算方法和限制性多电子组态相互作用方法(MECI)并根据Onsager方程计算溶剂效应,成功地对9-氨基吖啶(AMAR)、9,10-二甲氧基-2-甲基蒽(DMAN)、9-甲基蒽(AN)、α-萘甲酸乙酯(NAAC)四种有机发色团分子的吸收跃迁能进行了理论计算,吸收跃迁能理论计算值与光谱实验测定值相关分析表明,它们具有相当好的相关系数,显示半经验量子化学方法可以作为预测有机发色团光谱性质的有效计算方法.     

Kr-CS2体系势能面及束缚态能级的理论研究

本文采用单双迭代(包括非迭代三重激发)耦合簇CCSD(T)方法,对C、S原子采用aug-cc-PVTZ基组,对Kr原子采用cc-PVTZ –DK基组,并且加上中心键函数(3s3p2d2f1g),计算得到Kr-CS2体系的势能面。该势能面为T型结构,存在一个全局极小值和两个等价的局域极小值。全局极小值位于R =7.05 a0,θ= 90°处,势能值为-396.194 cm-1。两个局域极小值分别位于R = 10.15 a0,θ= 0°和180°处,势能为-243.647 cm-1。利用该势能面,通过数值求解相应的薛定谔方程,计算得出体系J≤10的束缚态能级及微波谱跃迁频率,并通过跃迁频率拟合得到相应的光谱常数。     

CH3CH2O及CH3CHOH与HO2反应机理的理论研究

采用CCSD(T)/cc-pVTZ//B3LYP/6-311++G(2df,2p)水平上对CH3CHOH + HO2和CH3CH2O + HO2反应体系的单、三重态反应机理进行了详细的理论研究.计算结果表明,CH3CHOH + HO2反应主要发生在单重态势能面上,其中四条通道均为快速自发过程;CH3CH2O + HO2反应在三重态势能面上的通道CH3CH2O + HO2 → 3IM11 → 3TS11 → P11 (CH3CH2OH + 3O2)为动力学和热力学的优势路径. 大气中CH3CHOH比CH3CH2O更容易稳定存在.