Dissociation and ionization of diatomic molecules in laser fields - full dimensional ab-initio description including electron-nuclear correlations

该项目的关注点是最近开发的“非绝热跳跃量子分子动力学”（NA-QMD-H）方法的扩展，以明确地包括在谐波，任意长脉冲的分子动力学的理论描述中的外部激光场。 新的方法允许全维（包括旋转，振动和电子激发）的激光驱动的离解和电离的两个原子分子，包括在核动力学的量子效应的同时从头计算描述。因此，这种方法是电子和原子核的完全含时薛定谔方程的近似解。这是德累斯顿NA-QMD方法多年发展的最终目标（见“本征Vorarbeiten”一节）。 这一目标将通过对原子核的近似量子力学处理来实现，其中经典轨迹在量子力学确定的能量表面上传播。这些表面的选择是至关重要的。在预期的方法中，将应用Floquet表面（在脉冲期间）和Born-Oppenheimer表面（用于脉冲之后的弛豫动力学）。与量子力学确定的单表面之间的跃迁速率（“跳跃”），这应该允许一个精确的描述激光驱动的分子动力学，包括电子核相关。对于H2+，我们已经有了这种方法的经验。 具有挑战性的方法扩展到两个原子的多电子分子是本项目的较窄的关注。这里首次使用与该分子对应的Kohn-Sham系统的密度泛函理论Floquet表面。该方法的另一个新的和重要的点是通过中性、单个或多个电离分子的表面之间的跳跃来描述光电离，这样就可以完整地描述所有（相关）电离通道。对于这个项目，已经与海德堡的Max-Planck-Institut für Kernphysik（MPIK）签订了合作协议（见附件）。在MPIK中，使用反应显微镜进行关于解离和电离的运动学完整实验。 在与MPIK协商后，应首先对氩二聚体进行具体计算（随后也对其他惰性气体以及O2和N2进行计算），并将计算结果与实验结果进行比较，以帮助解释。此外，模拟泵探测实验的解释计划。新方法允许在计算中明确地包括泵浦脉冲和探测脉冲。一个共同的目标，除其他外，是调查在何种程度上的分子动力学可以通过适当选择的激光参数进行操纵。

The concern of this project is the extension of the recently developed "Non-Adiabatic Quantum Molecular Dynamics with Hopping" (NA-QMD-H) method to explicitly include an external laser field in the theoretical description during the molecular dynamics in harmonic, arbitrary long pulses. The new approach allows for an full-dimensional (including rotation, vibration, and electronic excitation) simultaneous ab-initio description of the laser-driven dissociation and ionization of two-atomic molecules, including quantum effects in the nuclear dynamics. This approach therefore is an approximative solution of the full time-dependend Schrödinger equation for electrons and nuclei. It is the ultimate goal of many years of development of Dresden's NA-QMD method (see Section "Eigene Vorarbeiten"). This goal shall be achieved with an approximate quantum-mechanical treatment of the nuclei, where classical trajectories are propagated on quantum-mechanically determined energy surfaces. The choice of these surfaces is crucical. In the intended method, Floquet surfaces (during the pulse) and Born-Oppenheimer surfaces (for the relaxation dynamics following the pulse) will be applied. In connection with quantum-mechanically determined transition rates between single surfaces ("hopping"), this should allow for an accurate description of the laser-driven molecular dynamics including electron-nuclear correlations. For H2+, we already have experience with this approach. The challenging extension of the method to two-atomic multi-electron molecules is the narrower concern of the present project. For the first time, density-functional-theory-Floquet surfaces of the Kohn-Sham system corresponding to the molecule shall be used here. A further new and important point of the method is the description of photoionization by hopping between surfaces of the neutral, single, or multiple ionized molecule, such that a complete description of all (relevant) ionization channels should be possible.For this project a cooperation agreement with the Max-Planck-Institut für Kernphysik (MPIK) Heidelberg has been concluded (see attachments). At the MPIK, kinematically complete experiments concerning the dissociation and ionization are performed using a reaction microscope. In consultation with the MPIK, specific calculations shall be done at first for argon dimers (later also for other noble gases as well as O2 and N2), the results shall be compared to the experimental findings and help with their interpretation. Furthermore, simulations for the interpretation of pump-probe experiments are planned. The new method allows for an explicit inclusion of the pump and the probe pulse in the calculation. A common aim, among others, is to investigate to what extent the molecular dynamics can be manipulated by suitable choices of the laser parameters.