中文摘要：

贫氢分子CnH是燃烧火焰、行星大气中的重要的中间体.这些分子与其它一些分子或自由基的反应在星际化学中起着非常重要的作用.虽然这些分子的电子结构和光谱性质已经进行了广泛的研究,但是研究这些反应的机理和动力学性质也是亟需的.因此,我们采用直接动力学方法对线性分子丁二炔自由基C4H（CCCCH）夺氢气（H2）分子中HAT的反应的微观机理和动力学性质进行了理论研究.本研究分别在BB1K/6-311＋G（2d,2p）,B3LYP/6-311＋G（2d,2p）和M06-2x/6-311＋G（2d,2p）水平上优化得到了各稳定点的结构及振动频率.为了得到更为可靠的反应能量和势能面信息,在BB1K/6-311＋G（2d,2p）优化结构的基础上用CCSD（T）/aug-cc-pVTZ水平进行了单点能量校正.对于此反应研究了两条不同的氢吸附通道,C4H（C1C2C3C4H）中的C1和C4分别吸氢,即通道1（R1）和通道2（R2）.计算得出：通道1和通道2的能垒分别为3.58 kcal/mol和26.56 kcal/mol,结果表明C4H中C1端吸氢是主要通道.反应过程中的电子转移可以为理解氢原子转移（HAT）提供重要的线索,因此,我们利用NBO对反应过程中的电子转移行为进行了详细的分析.本工作运用经典过渡态理论（VTST）与变分过渡态理论（CVT）和变分过渡态理论结合小曲率隧道效应校正（CVT/SCT）的方法计算了该反应在40～1000 K温度区间的速率常数.除对于最低频率的配分函数采用了阻尼内转动近似外,其它频率都采用谐振子模型处理.计算得到的总的CVT/SCT反应速率常数与已有的实验值符合得很好.我们还提供了40～1000K温度范围内的三参数Arrhenius表达式.这些公式有利于今后在较宽的温度范围内迄今没有实验数据的反应的研究.

英文摘要：

Hydrogen-deficient molecules have been implicated as the key intermediates in the combustion, planetary at- mospheres, and so on. Their reactions with other molecules and/or radicals play important roles and are hot topic in interstel- lar chemistry. Although extensive efforts have been addressed on the electronic and spectroscopic properties of these mole- cules, continued extensive research, for example the kinetics and mechanism of their reactions, is still desirable. Therefore, we investigated the hydrogen abstraction （HAT） reaction by the linear butadiynyl radical Call （CCCCH） from hydrogen （H2） by direct ab initio kinetics over a wide temperature range 40~1000 K theoretically at the CCSD（T）/aug-cc-pVTZ// BB 1 K/6-311 ＋ G（2d,2p） level of theory. The optimized geometries and frequencies of the stationary points are calculated at the BB1K/6-311 ＋G（2d,2p）, B3LYP/6-311 ＋G（2d,2p） and M06-2x/6-311 ＋G（2d,2p） level, respectively. To obtain more reliable reaction energies and barrier heights, high-level single-point calculations for the stationary points have been per- formed at the CCSD（T）/aug-cc-pVTZ by using BB 1K/6-311 ＋G（2d,2p） Cartesian coordinates. Two different hydrogen ab- straction channels by Cl and C4 of C4H （C1C2C3C4H） have been explored, namely, Channel 1 （R1） and Channel 2 （R2）. The activation barrier heights of Channel 1 and Channel 2 are 3.58 kcal/mol and 26.56 kcal/mol, respectively. The results indicate that C1 position of the C4H is a more reactive site. The electron transfer evolution may offer important clues for understand- ing hydrogen atom transfer （HAT）, we therefore analyzed the electron transfer behaviors by NBO in detail. The theoretical rate constants were predicted by the conventional variational transition state theory （VTST）, canonical variational transi- tion-state theory （CVT） incorporating a small-curvature tunneling correction （CVT/SCT） method. For the lowest frequency, the partition function is evaluate