Transition state in atomic physics
Transition state in atomic physics
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DOI：
10.1103/physreva.60.3833
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发表时间：
1999-11
影响因子：
2.9
通讯作者：
C. Jaffé;D. Farrelly;T. Uzer
中科院分区：
文献类型：
--
作者：
C. Jaffé;D. Farrelly;T. Uzer
过渡态是现代反应动力学理论的基础：本质上，过渡态是所有反应轨迹必须穿过的相空间结构。而过渡态理论~TST！由于该理论主要用于化学物理学，因此可以将该理论应用于涉及某种形式反应的任何碰撞问题，从而发挥相当大的优势。特别令人感兴趣的是发生混沌散射或半散射的系统，例如里德伯原子在外部场中的电离。在本文中，氢原子在交叉电场和磁场中的电离动力学被证明具有过渡态：我们计算周期轨道分割面〜PODS！当投影到配置空间时，发现它不是分割表面。尽管之前已经认识到 PODS 发生在相空间而不是配置空间中的可能性，但据我们所知，这是第一个实际例子：它的起源直接追溯到哈密顿量中速度相关项的存在。我们的研究结果表明 TST 是理解里德伯原子在速度相关力存在下电离的首选方法。为了演示这个 TST 用于〜i！揭示电离的多重散射机制，〜ii！计算电离率。在此过程中，我们还开发了一种计算截面表面的方法，该方法使用周期轨道来定义表面，并检查动力学的分形性质。 @S1050-2947~99!06710-4#
The transition state is fundamental to modern theories of reaction dynamics: essentially, the transition state is a structure in phase space that all reactive trajectories must cross. While transition-state theory ~TST! has been used mainly in chemical physics, it is possible to apply the theory to considerable advantage in any collision problem that involves some form of reaction. Of special interest are systems in which chaotic scattering or half-scattering occurs such as the ionization of Rydberg atoms in external fields. In this paper the ionization dynamics of a hydrogen atom in crossed electric and magnetic fields are shown to possess a transition state: We compute the periodic orbit dividing surface ~PODS! which is found not to be a dividing surface when projected into configuration space. Although the possibility of a PODS occurring in phase space rather than configuration space has been recognized before, to our knowledge this is the first actual example: its origin is traced directly to the presence of velocity-dependent terms in the Hamiltonian. Our findings establish TST as the method of choice for understanding ionization of Rydberg atoms in the presence of velocity-dependent forces. To demonstrate this TST is used to ~i! uncover a multiple-scattering mechanism for ionization and ~ii! compute ionization rates. In the process we also develop a method of computing surfaces of section that uses periodic orbits to define the surface, and examine the fractal nature of the dynamics. @S1050-2947~99!06710-4#