Dynamic electron correlations in one- and two-center atomic systems

在微观尺度上，物质的结构和时间演化关键取决于电子的相关性。相关电子动力学负责自然界中各种各样的过程，从磁性的起源和氦氖激光的功能到生物分子中的能量转移。电子相关的一些最明显的表现出现在原子系统中，由于现代实验技术，它们可以被深入研究。例如，反应显微镜或离子存储环允许在单个原子粒子的微观尺度上详细探索量子过程。在不久的将来，动态电子相关实验的前景要求发展复杂的理论处理。它们将有助于正确解释实验数据，并揭示电子相关性在特别有趣的情况下的作用：特别是当原子电子(i)受到极端高场环境的影响，或（ii）位于两个不同的位置时，这两个位置要么几乎处于静止状态，相隔相对较远，要么以较高的相对速度运动。在这个理论项目中，我们的目标是双重的。首先，我们想研究受高电荷离子强电场作用的自由电子和深束缚电子之间的动态关联。对共振电子散射和电子碰撞电离过程进行详细探讨，包括相对论相关效应，如Breit相互作用。计划在欧洲和中国的储存环设施进行相应的实验研究。我们还将讨论谐振激光场的应用在多大程度上可以影响甚至控制微观尺度上的电子相关性的问题。其次，我们想探索由双中心电子相关驱动的动态过程。它们尤其出现在由范德华力束缚的大双原子分子中。虽然近年来已经成功地研究了这种双中心系统中的动态电子相关性，但对入射电子束的分子响应知之甚少。我们的目标是研究不对称双原子范德华分子的光子和电子碰撞电离，其中主要通道预计依赖于位于两个分离良好的原子中心的电子之间的动态关联。此外，我们还将研究光离子与氢和氦原子的快速碰撞中相互电离的双中心电子相关效应，包括激光场辅助下的碰撞。我们的结果可能会在我们对单中心和双中心电子相关性的理解之间建立一座桥梁，并指导新的实验。

The structure and time evolution of matter on a microscopic scale crucially depend on electron correlations. Correlated electron dynamics is responsible for a wide variety of processes in nature, ranging from the origin of magnetism and the functionality of a helium-neon laser to the energy transfer in biomolecules. Some of the clearest manifestations of electron correlations appear in atomic systems where they can be studied in great depth due to modern experimental techniques. Reaction microscopes or ion storage rings, for example, allow for a detailed exploration of quantum processes at the microscopic scale of single atomic particles. The prospect of corresponding experiments on dynamic electron correlations in the near future calls for the development of sophisticated theoretical treatments. They shall help to correctly interpret the experimental data and to reveal the role of electron correlations in especially interesting situations: in particular, when atomic electrons are (i) subject to extreme high-field environments or (ii) located at two different sites which, either, are almost at rest and separated by relatively large distances, or move at high relative velocity.In this theoretical project, our goals are twofold. First, we want to study dynamic correlations between free and deeply bound electrons which are subject to the very strong electric field of a highly charged ion. The processes of resonant electron scattering and electron-impact ionization shall be explored in detail, including relativistic correlation effects, such as the Breit interaction. Corresponding experimental studies are planned at storage-ring facilities in Europe and China. We will also address the question as to which extent electronic correlations on the microscale can be influenced and even controlled by the application of a resonant laser field.Second, we want to explore dynamic processes driven by two-center electron correlations. They arise, in particular, in large diatomic molecules bound by van-der-Waals forces. While dynamic electron correlations in such two-center systems have successfully been investigated in recent years, there exists only limited knowledge about the molecular response to incident electron beams. We aim to study photon- and electron-impact ionization of asymmetric diatomic van-der-Waals molecules, where the dominant channel is expected to rely on the dynamic correlation between electrons located at the two well-separated atomic centers. Besides, we shall also study two-center electron correlation effects in mutual ionization occurring in fast collisions of light ions with hydrogen and helium atoms, including collisions assisted by a laser field.Our results may be able to form a bridge between our understanding of one-center and two-center electron correlations and guide the way towards new experiments.