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

红外光激发的吸附物振动在化学和物理的许多领域发挥着重要作用。例如光谱学、模式选择化学、信息技术或界面上的能量传递和存储。作为“开放量子系统”，表面的振动也引起了相当大的基本兴趣，特别是在所谓的“非马尔可夫”行为和长时间内分子系综中相干性的保存的背景下。本项目利用量子动力学方法，从理论上研究了半导体或绝缘体表面原子或分子的激发和随后的弛豫振动的基本过程的动力学。基于我们第一个资助期的工作，以下目标将沿着这些思路解决：对于氢和氘吸附在重建硅表面的例子，(1)将执行“还原”的系统测试，开放系统密度矩阵理论将与使用时间相关Schrödinger方程的系统浴动力学的“精确”处理进行比较；(2)迄今为止发展的模型哈密顿量应得到扩展和有效，应采用基于数值波函数的方法来处理由振动-声子耦合引起的红外激发和弛豫；(3)研究红外激发和弛豫之间的相互作用，特别是在耗散环境中实现模式选择激发。(4)对于第二个模型系统，NaCl（100）表面上的一氧化碳，应该开发粗粒度密度矩阵模型来描述红外激发和随后吸附分子整体中的振动能量传递。在这里，“能量池”现象尤其令人感兴趣，因为目前的实验表明存在振动非常高激发的CO分子。

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.