Laser-driven electron dynamics in molecules

超短的、通常是量身定做的激光脉冲非常成功地揭开了电子在原子、小分子和表面上的电子运动的动力学细节，在电子的自然时间尺度上为阿秒。为了对“阿秒化学”做出贡献，在这个项目中，我们希望应用和改进基于显式相关的、基于波函数的方法来探测和控制激光脉冲激发分子中的多电子动力学：从小到大。具体地说，我们希望应用以原子轨道(AO)和固定核近似表示的含时组态相互作用(TD-CI)作为主要工作。这是有效的，同时也很容易用于处理量子化学的困难情况，如远程电荷转移和静态关联。对于改进，将采用各种方法来处理电离损失、核运动和环境影响。此外，TD-CI一方面将与基于密度泛函的方法进行比较(对于较大的分子)，另一方面将与分子薛定谔方程的数值“精确”解进行比较(对于小分子)。我们将使用解析脉冲或由各种自动化策略构造的超短飞秒激光脉冲，特别是最优控制理论(OCT)和随机脉冲优化(SPO)。主要有两条应用路线：1.电子波包的产生和控制；2.分子对激光的非线性响应及其主动控制。用激光脉冲控制电子波包的目的是控制分子中的电子运动。具体的目标是在分子系统中强制进行定向的、远程的电荷转移，或者，作为一个迄今为止纯粹的假设概念，去关联电子。关于非线性响应，我们对分子的高次谐波产生(HHG)特别感兴趣。具体地说，我们希望研究HHG作为区分有机异构体或产生超短激光脉冲的光谱工具的性能。对于较小的系统，我们将尝试主动控制HHG信号，并研究它们对电离损失和核运动的依赖关系。

Ultrashort, often tailored, laser pulses have been very successful for unravelling dynamical details of electronic motion in atoms, small molecules and at surfaces, on the electrons' natural timescale of attoseconds. In an attempt to contribute towards "attosecond chemistry'', in this project we wish to apply and improve explicitly correlated, time-dependent wavefunction-based methods to probe and control, the many-electron dynamics in laser-pulse excited molecules: from small to large ones.Specifically, we wish to apply Time-Dependent Configuration Interaction (TD-CI) expressed in an Atomic Orbital (AO) basis and in the fixed-nuclei approximation as the main working horse. This ansatz is efficient and at the same time readily available for treating quantum chemically difficult cases such as long-range charge transfer and static correlation. For refinement, various approaches towards treating ionization losses, nuclear motion and effects of an environment will be applied. Also, TD-CI will be benchmarked against density functional based methods on the one-hand side (for larger molecules), and against numerically "exact" solutions of the molecular Schrödinger equation on the other (for small molecules). We shall use either analytic pulses, or shaped ultrashort femtosecond laser pulses constructed by various automated strategies, notably Optimal Control Theory (OCT) and Stochastic Pulse Optimization (SPO).Two main lines of applications will be followed: 1. The creation and control of electronic wavepackets and 2. the non-linear response of molecules to lasers and its active control.The control of electronic wavepackets by laser pulses serves the purpose of steering electronic motion in molecules. Specific goals are to enforce directed, long-range charge transfer in molecular systems, or, as a so far purely hypothetical concept, to de-correlate electrons. Concerning non-linear responses, we are particularly interested in High Harmonic Generation (HHG) in molecules. Specifically, we wish to investigate the performance of HHG as a spectroscopic tool to discriminate between organic isomers, or to create ultrashort laser pulses. For smaller systems, we shall try to actively control HHG signals and investigate their dependence on ionization losses and nuclear motion.