Vibrational Circular Dichroism and Electronic Currents from First Principles

振动圆二色谱(VCD)是一种新兴的光谱技术，在学术界和工业界的应用范围越来越广。由于左、右圆偏振光吸收的差异，VCD可以认为是“手性红外光谱”。通过将记录的光谱分配给从理论计算获得的结构信息，它已成为确定绝对构型的宝贵工具。然而，VCD对手性中心周围的超分子效应高度敏感，无论是溶液光谱对溶剂的依赖还是固体中手性晶体堆积的影响。关键的一点在于解释实验结果时可参考的有效理论模型的可用性。由于缺乏合适的理论模型，VCD的许多应用都没有实现。近年来，在负担得起的计算能力的不断增强的推动下，理论方法的财富稳步增长。创新的方法允许现实的模拟，可以被认为是“虚拟实验”。该项目旨在通过从头算分子动力学(AIMD)和核速度微扰理论(NVPT)的形式相结合来推动计算化学的里程碑式的创新。NVPT的理论框架直到最近才被应用到CPMD代码中，并等待着大量的应用。AIMD+NVPT是一种基于非简谐自由能的准确采样来计算VCD谱的有吸引力的方法；前面的工作已经强调了如果这种方法的影响。这一成功之后，这个项目将继续下去。然而，光谱学还有更多的应用，但有机化学和更基础的量子化学也构成了拟议研究的重要第二支柱。后者还旨在使研究人员的形象多样化，受益于东道主研究人员在世界领先的量子物理和化学计算机构的网络和专业知识。为了以极具说明性的方式将理论结果传达给广大受众，该项目明确地致力于设计具有教育意义的可视化手段，并通过一个全面的Python包来提高技术的易用性。

Vibrational circular dichroism (VCD) is an uprising spectroscopic technique with an increasing scope of applicability in both, academia and industry. Referring to the absorption difference of left- and right-circularly polarised light, VCD can be considered as “chiral IR spectroscopy”. It has become an invaluable tool in the determination of absolute configurations by assigning recorded spectra to structural information obtained from theoretical calculations. Yet, VCD is highly sensitive towards supramolecular effects around the chiral centre, be it the dependence of a solution spectrum on the solvent or the influence of chiral crystal packing in solid-state. A crucial point lies in the availability of efficient theoretical models that are to be referred to when interpreting experimental results. Many applications of VCD do not materialize due to the lack of suitable theoretical models. The recent years saw the wealth of theoretical methods growing steadily – fueled by continuous augmentation of affordable computational power. Innovative approaches allow for realistic simulations that can be considered as "virtual experiments". This project aims to push forward landmark innovations of computational chemistry by combining ab initio molecular dynamics (AIMD) and the formalism of Nuclear Velocity Perturbation Theory (NVPT). The theoretical framework of NVPT has only recently been implemented into the CPMD code and awaits numerous applications. AIMD+NVPT are an attractive means to compute VCD spectra based on an accurate sampling of anharmonic free energies; the preceding work has already underlined the impact if this method. This success will be followed up by this project. Yet, there are many more applications in spectroscopy, but also organic chemistry and more fundamental in quantum chemistry that form the important second pillar of the proposed research. The latter also aims for diversifying the profile of the researcher, benefiting from the host researcher's network and expertise in a world-leading institution in quantum physics and chemical computation. To communicate the theoretical results in a highly illustrative fashion to a broad audience, this project explicitly puts effort into devising instructive and educational means of visualization and to improve the techniques' ease of use through a comprehensive python package.