共查询到18条相似文献,搜索用时 171 毫秒
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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. 相似文献
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采用含时量子波包方法结合二阶分裂算符传播子对初始态为(v=0, j=0)的O~++H_2→OH~++H反应体系在0.01—1.00 eV的碰撞能范围内进行了态分辨理论水平上的动力学计算.对反应概率、积分截面、微分截面以及固定初始态的热速率常数等动力学信息进行了计算并与文献报道的实验和理论结果进行了比较.结果表明本文的理论结果与实验结果十分符合.从微分截面的散射信息可知,在低碰撞能范围内,插入反应机制在反应中占据主导地位.随着碰撞能的增加,反应机制逐渐由插入机制变为抽取反应机制. 相似文献
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碰撞反应Ca+C2H5Br和Ca+nC3H7Br产物CaBr的内能态分布 总被引:1,自引:0,他引:1
采用准经典轨线方法研究了碰撞反应Ca+C2H5Br和Ca+nC3H7Br产物CaBr的内能态分布,计算了产物分子CaBr的平均振动、转动和平动能量以及总可资用能量.结果表明,当碰撞能为7.54kJ/mol时,产物的能量主要为振动能量;随着碰撞能增加,产物的平动能和转动能增加,而振动能略微减小,最可几振动态向较低振动能级移动;反应物分子内能态分布对产物分子的内能态分布影响很小;反应基团越大,产物的振动能占总可资用能量的比例就越高.碰撞反应Ca+C2H5Br和Ca+nC3H7Br均存在两条竞争的反应路径迁移相碰和直接反应路径.前者产生高振动激发态产物CaBr,后者引起C-Br键断裂.当碰撞能增加时,两种反应均倾向于后者. 相似文献
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对SiH4+ H→H2+SiH3反应体系应用SVRT模型进行了4维的量子动力学计算.将得到的速率常数与实验数据以及其他理论方法进行比较,得出了一些有意义的结论,并与CH4+H→H2+CH3反应在同种理论模型下做了对比,较好的与实验相吻合.最后验证了理论方法以及势能面的正确性. 相似文献
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H+SO2→OH+SO反应在燃烧、大气和星际化学中都扮演着重要角色. 它还是具有深势阱中间体形成的典型反应,是检验速率理论和提供有趣反应动力学现象的理想候选反应. 基于之前构建的全维高精度势能面,本文对该反应进行了准经典动力学研究. 在1400 K≤T≤2200 K的温度范围内,计算值重现了实验速率常数. 当反应物SO2处于振-转基态,在31.0∽40.0 kcal/mol的碰撞能范围内,计算得到的积分反应截面随碰撞能增加;在40∽55 kcal/mol的碰撞能范围内,积分反应截面几乎不受碰撞能影响. 产物角度分布呈现对称的前后向双峰结构. 本文还分析了产物OH和SO的振动态分布. 相似文献
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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. 相似文献
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使用三维含时波包方法在两个势能面上研究了Cl+H2(D2)反应.所使用的两个势能面都是从CW(Capecchi和Wener)势能面得到的,第一个是CW势能面的基态面加自旋轨道耦合修正,第二个是CW势能面的基态面没有自旋轨道耦合修正.在这两个势能面上得到了碰撞能从0.1到1.4 eV的积分截面以及反应几率.对于Cl与D2反应,考虑自旋轨道耦合后由于势垒高度的增加反应截面向高能处有一个平移,但Cl与H2反应在低能处的反应活性反而增大了,原因是虽然自旋轨道耦合效应增加了势垒高度,同时减小了势垒宽度,隧道效应更加明显,而隧道效应在低能处起着比较重要的作用,所以反应活性比较大.当碰撞能大于0.7 eV时,没有考虑自旋轨道耦合时势垒高度较低,因而反应活性较大. 相似文献
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Brouard M Burak I Marinakis S Minayev D O'Keeffe P Vallance C Aoiz FJ Bañares L Castillo JF Zhang DH Xie D Yang M Lee SY Collins MA 《Physical review letters》2003,90(9):093201
The absolute value of the cross section for the abstraction reaction between fast H atoms and H2O has been determined experimentally at a mean collision energy of 2.46 eV. The OH population distribution at the same mean energy has also been determined. The new measurements are compared with state-of-the-art quantum mechanical and quasiclassical scattering calculations on the most recently developed potential energy surface. 相似文献
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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. 相似文献
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Kendrick BK Jayasinghe L Moser S Auzinsh M Shafer-Ray N 《Physical review letters》2000,84(19):4325-4328
We present experimental verification of predicted resonance structure in the energy dependence of the H+D2 reaction. Specifically we predict and observe a broad resonance in the H+D2-->HD(v(') = 0,j(') = 7)+D reaction at a collision energy of 0. 94 eV. This resonance structure is roughly Gaussian with a full width at half maximum of 0.1 eV. These results represent the first experimentally observed resonance structure in the fundamental H+H2 reaction system. 相似文献
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Energy and rotation-dependent stereodynamics of H(~2S) + NH(a~1?) → H_2(X~1Σ_g~+) + N(~2D) reaction 下载免费PDF全文
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. 相似文献
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利用含时波包方法对D+HS交换和抽取通道进行量子动力学研究,动力学计算中所采用的势能面由高精度从头算能量点构建.在平动能0.0~2.0 eV区间内计算了反应物初始振转基态时的总反应几率和积分反应截面,并且计算了初始振动激发态对积分反应截面的影响.所有动力学计算均考虑了科里奥利耦合效应.在低平动能时抽取通道在反应中占主导地位,而交换通道在高平动能时占主导地位.在整个所研究的平能能区间内,反应物HS的振动激发对抽取和交换通道反应都有增强作用. 相似文献
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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. 相似文献
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After the Big Bang, chemical reactions of hydrogen with LiH and its isotopic variants played an important role in the late stage of recombination. Moreover, these reactions have attracted the attention of experts in the field of molecular dynamics because of its simple structure. Electronically non-adiabatic effects play a key role in many chemical reactions, while the related studies in LiH2 reactive system and its isotopic variants are not enough, so the microscopic mechanism of this system has not been fully explored. In this work, the microscopic mechanism of H + LiD reaction are performed by comparing both the adiabatic and non-adiabatic results to study the non-adiabatic effects. The reactivity of R1 (H + LiD → Li + HD) channel is inhibited, while that of R2 (H + LiD → D + LiH) channel is enhanced when the non-adiabatic couplings are considered. For R1 channel, a direct stripping process dominates this channel and the main reaction mechanism is not influenced by the non-adiabatic effects. For R2 channel, at relatively low collision energy, the dominance changes from a rebound process to the complex-forming mechanism when the non-adiabatic effects are considered, whereas the rebound collision approach still dominates the reaction at relatively high collision energy in both calculations. The presented results provide a basis for further detailed study on this importantly astrophysical reaction system. 相似文献
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Isotope effect on the stereodynamics for the collision reaction H+LiF(v = 0, j = 0) → HF+Li 下载免费PDF全文
Stereodynamics for the reaction H+LiF(v=0, j=0) → HF+Li and its isotopic variants on the ground-state (1 2 A′) potential energy surface (PES) are studied by employing the quasi-classical trajectory (QCT) method. At a collision energy of 1.0 eV, product rotational angular momentum distributions P (θr), P (φr), and P (θr ,φr), are calculated in the center-of-mass (CM) frame. The results demonstrate that the product rotational angular momentum j′ is not only aligned along the direction perpendicular to the reagent relative velocity vector k, but also oriented along the negative y axis. The four generalized polarization-dependent differential cross sections (PDDCSs) are also computed. The PDDCS 00 distribution shows a preferential forward scattering for the product angular distribution in each of the three isotopic reactions, which indicates that the title collision reaction is a direct reaction mechanism. The isotope effect on the stereodynamics is revealed and discussed in detail. 相似文献