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

直觉表明，电子和原子核应该在电子绝热的单分子过程中一起流动，例如电子基态的化学反应、振动或解离。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(CENFD)进行量子动力学模拟。然而，自从1926年薛定谔方程被发现以来，这一领域一直没有取得持久的进展，直到最近。主要的障碍是Born-Oppenheimer近似(BOA)，尽管BOA在量子化学和其他量子反应动力学领域得到了相当成功的应用。最近，我们与来自美国的客座教授Dennis J.Diestler教授和柏林的Beate Paulus教授一起，通过计算最简单的系统的CENFD，即在电子基态(即原型)振动时排列的H2+，实现了这一领域的突破。结果是通过两种独立的方法得到的：一种是谱方法，其中波函数被表示为完全哈密顿量的振动本征函数的线性组合；另一种是与Diestler教授合作发展的“标度耦合通道”方法，它只利用BOA波函数作为分层程序的输入。谱方法提供了准确的CENFDs，可作为评估尺度耦合通道结果质量的参考。这两个人对原型的看法非常一致。这项工作的目的是将这一有希望的方法扩展到更苛刻的过程，以及具有两个或更多电子的双原子系统的更复杂的排列或各向同性分布。它们包括：在原型中，在不对称的单电子系统中，例如HD+，以及在具有单价电子的对称和不对称系统(例如，Na2+和LiH+)中，振动和解离之间的振动恢复、解离和竞争；在两电子系统中，例如双电子原型，或者在具有两个或更多活跃价电子的系统中，例如Na2和LiH，以及F2中，类似的过程。这些例子将第一次显示电子-电子斥力对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.