Coherent electronic and nuclear flux densities during adiabatic unimolecular processes in diatomic molecules

直觉告诉我们，电子和原子核应该在电子绝热的单分子过程中一起流动，例如在电子基态的化学反应、振动或离解。飞秒和阿秒化学的实验进展要求对相干电子和核通量密度进行量子动力学模拟。然而，自1926年发现薛定谔方程以来，直到最近，这一领域都没有取得持久的进展。主要的障碍是玻恩-奥本海默近似（BOA），尽管BOA在量子化学和量子反应动力学的其他领域中应用得相当成功。最近，我们与来自美国的客座教授Dennis J. Diestler教授和Beate Paulus教授（FU柏林）一起在这一领域取得了突破，通过计算最简单系统的CENFD，即电子基态的对齐H2+（即，原型）正在经历振动。结果是通过两种独立的方法获得的：一种是谱方法，其中波函数被表示为完整哈密顿量的振动本征函数的线性组合;与Diestler教授合作开发的"缩放耦合通道”方法，它只利用BOA波函数作为分层过程的输入。光谱方法提供了准确的CENFD，作为评估缩放耦合通道结果的质量的参考。两者在原型上非常一致。这里提出的工作的目的是将这种有前途的方法扩展到更苛刻的过程和更复杂的对齐或各向同性分布的双原子系统与两个或更多的电子。其中包括：振动回复、解离和振动与解离之间的竞争，在原型中，在不对称单电子系统中，例如HD+，以及在具有单个价电子的对称和不对称系统中（例如，Na ~（2+）和LiH ~+）;在双电子系统中的类似过程，如H2，双电子原型，或在具有两个或更多个活性价电子的系统中，如Na 2和LiH，以及F2。这些例子将首次显示电子-电子排斥对CENFD的影响。

Intuition suggests that electrons and nuclei should flow together during electronically adiabatic unimolecular processes such as chemical reactions, vbrations or dissociations in the electronic ground state. Experimental advances in femto- and attosecond chemistry call for quantum dynamical simulations of coherent electronic and nuclear flux densities (CENFD). No lasting progress had been made in this field, however, since the discovery of the Schrödinger equation in 1926, until very recently. The main obstacle has been the Born-Oppenheimer approximation (BOA), irrespective of the fact that the BOA is applied quite successfully in quantum chemistry and other domains of quantum reaction dynamics. Recently we, together with Prof. Dr. Dennis J. Diestler, a guest professor from the USA and Prof. Beate Paulus (FU Berlin), achieved a breakthrough in this field, by calculating the CENFD for the simplest system, namely aligned H2+ in the electronic ground state (i.e., the prototype) undergoing vibration. The results were obtained by two independent methods: a ¿spectral method¿, in which the wave function is expressed as a linear combination of vibronic eigenfunctions of the complete Hamiltonian; the ``scaled coupled channels" method, developed in cooperation with Prof. Diestler, which utilizes only the BOA wave function as ¿input¿ to a hierarchical procedure. The spectral method provides accurate CENFDs, which serve as references for assessing the quality of scaled coupled-channels results. The two are in excellent agreement for the prototype. The aim of the work proposed here is to extend this promising approach to more demanding processes and to more complex aligned or isotropic distributions of diatomic systems with two or more electrons. These include the following: vibrational revivals, dissociation, and competition between vibration and dissociation, in the prototype, in asymmetric one-electron systems, such as HD+, and in symmetric and asymmetric systems with a single valence electron (e.g., Na2+ and LiH+); analogous processes in two-electron systems, such as H2, the two-electron prototype, or in systems with two or more active valence electrons, such as Na2 and LiH, and F2. These examples will show, for the first time, the influence of electron-electron repulsion on the CENFDs.