Reduced and full system-bath quantum dynamics of IR-driven adsorbate vibrations

吸附振动，激发红外（IR）光，在化学和物理的许多领域发挥作用。例如光谱学、模式选择化学、信息技术或界面处的能量转移和存储。作为“开放量子系统”，表面振动也具有相当大的基本兴趣，特别是在所谓的“非马尔可夫”行为和分子系综中长时间内保持内聚性的背景下。在目前的项目中，在量子动力学方法的帮助下，从理论上研究了与半导体或绝缘体表面原子或分子振动的激发和随后的弛豫有关的基本过程的动力学。基于我们在第一个资助期的工作，将沿着这些路线实现以下目标：以氢和氘吸附在重建的硅表面上为例，（1）将进行“简化”的开放系统密度矩阵理论的系统测试，并与使用随时间变化的薛定谔方程的系统浴动力学的“精确”处理进行比较;（2）扩展到目前为止发展起来的模型哈密顿量，并应用有效的基于波函数的数值方法来处理由振动-声子耦合引起的IR激发和弛豫;（3）研究IR激发和弛豫之间的相互作用，特别是朝着耗散环境中的模式选择激发的目标。(4)对于第二个模型系统，NaCl（100）表面上的一氧化碳，应开发粗粒密度矩阵模型，以描述IR激发和随后的吸附分子系综中的振动能量转移。在这里，特别是，“能量池”的现象是感兴趣的，目前的实验表明，振动非常高度激发的CO分子的发生。

Adsorbate vibrations, excited by infrared (IR) light, play a role in many fields of chemistry and physics. Examples refer to spectroscopy, mode-selective chemistry, information technology, or energy transfer and storage at interfaces. As "open quantum systems", vibrations at surfaces are also of considerable fundamental interest, notably in the context of so-called "non-Markovian" behaviour and the preservation of coherences in molecular ensembles over long time periods. In the current project, the dynamics of elementary processes connected to the excitation and subsequent, relaxation of vibrations of atoms or molecules at semiconductor or insulator surfaces are studied theoretically with the help of quantum dynamical methods. Based on our work of the first funding period, the following aims will be addressed along these lines: For the example of hydrogen and deuterium adsorbed on a reconstructed silicon surface, (1) a systematic test of "reduced", open-system density matrix theory shall be performed in comparison to an "exact" treatment of system-bath dynamics using a time-dependent Schrödinger equation; (2) model Hamiltonians developed thus far shall be extended and efficient, numerical wavefunction-based methods shall be applied to treat IR excitation and relaxation caused by vibration-phonon coupling; (3) the interplay between IR excitation and relaxation shall be studied, notably towards the goal of mode-selective excitation in a dissipative environment. (4) For a second model system, carbon monoxide on a NaCl(100) surface, coarse grained density matrix models shall be developed to describe IR excitation and subsequent vibrational energy transfer in ensembles of adsorbed molecules. Here in particular, the phenomenon of "energy pooling" is of interest, for which current experiments show the occurrence of vibrationally very highly excited CO molecules.