An ab initio molecular dynamics and correlation function approach to dissipative adsorbate vibrational spectroscopy

耗散吸附物振动光谱的从头算分子动力学和相关函数方法

• 批准号: 449998565
• 负责人: Professor Dr. Peter Saalfrank
• 金额: --
• 依托单位: Lehrstuhl für Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/449998565?language=en
• 关键词: ab; initio; molecular; dynamics; correlation

The vibrations of atoms or molecules near solid surfaces are central to surface science. Probing the vibrations by steady-state and time-resolved spectroscopy provides "Fingerprints" which facilitate our understanding of elementary processes at surfaces, with the perspective to control and optimize them. The analysis of adsorbate vibrations by theory is often based on Normal Mode Analyses (NMA), which do not account for anharmonicity, temperature, mode couplings, and spectroscopic signals. They typically neglect also "Dissipation", i.e., relaxation caused by coupling to surface phonons and Electron Hole Pair (EHP) excitations, despite this can have a decisive influence on spectra. In this project we will go beyond NMA by using and extending Ab Initio Molecular Dynamics (AIMD) and AIMD with Electronic Friction (AIMDEF) methods, in combination with Time-Dependent Correlation Functions (TDCFs) for analysis and vibrational spectroscopy of adsorbates at surfaces. These methods account for all effects of above, give real-time information, have the potential to be extended to include quantum effects, and can be operated in an "on the fly'' mode without the need to precompute potential energy surfaces. This makes them applicable to complex systems which can hardly be treated otherwise. Specifically, we aim at a realistic modelling of vibration-phonon and / or vibration-EHP couplings and their influence on vibrational spectra, InfraRed (IR) and Vibrational Sum Frequency (VSF) spectra, both steady-state and time-resolved. Systems to be considered are hydrogen-covered silicon surfaces, water-covered metal and metal oxide surfaces, and metal surfaces in contact with hydrocarbons.

原子或分子在固体表面附近的振动是表面科学的核心。通过稳态和时间分辨光谱学来探测振动提供了“指纹”，这有助于我们理解表面的基本过程，并从角度来控制和优化它们。理论上对吸附振动的分析通常基于简正模式分析(NMA)，它没有考虑非谐性、温度、模式耦合和光谱信号。他们通常也忽略“耗散”，即耦合到表面声子和电子空穴对(EHP)激发所引起的弛豫，尽管这可能对光谱有决定性的影响。在这个项目中，我们将超越NMA，使用和扩展从头算分子动力学(AIMD)和带有电子摩擦的AIMD(AIMDEF)方法，并结合时间相关函数(TDCFs)用于表面吸附的分析和振动光谱。这些方法考虑了上述的所有影响，给出了实时信息，有可能扩展到包括量子效应，并且可以在不需要预先计算势能面的情况下以“即时”模式操作。这使得它们适用于很难用其他方法处理的复杂系统。具体地说，我们的目标是对振动-声子和/或振动-EHP耦合及其对稳态和时间分辨的振动光谱、红外(IR)和振动和频率(VSF)光谱的影响进行真实模拟。要考虑的系统是覆盖氢的硅表面，覆盖水的金属和金属氧化物表面，以及与碳氢化合物接触的金属表面。