First principles simulations of electronic spectroscopy for larger molecules

大分子电子光谱的第一原理模拟

• 批准号: 262942-2013
• 负责人: Nooijen, Martinus
• 金额: $ 5.03万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=594780
• 关键词: First; principles; simulations; electronic; spectroscopy

To gain a detailed understanding of molecular structures involved in complicated reactions, e.g. in a biological context, it is vital to be able to interpret a variety of spectroscopic measurements. For systems involving multiple transition metal atoms, viable spectroscopies include Resonance Raman, UV-VIS absorption, circular dichroism, magnetic circular dichroism, electron paramagnetic resonance, X-Ray near edge absorption, X-Ray emission, Mossbauer, XPS, NMR, and various time-resolved pump-probe techniques. The interpretation of spectra is a complicated process, and is currently often based on matching similarities to known spectra, and the use of simple models. The interpretation of the spectra, and perhaps even more importantly, the (structural) characterization of the system implied by the spectroscopy, can be greatly aided by reliable first principles theoretical simulations, the subject of this proposal. In the past we have developed technology to accurately simulate electronic spectroscopy for small molecules. The key ingredients involve the extraction of so-called vibronic model parameters from accurate coupled cluster type electronic structure calculations, and the evolution of quantum nuclear motion on multiple surfaces using non-adiabatic quantum wave packet dynamics. The key challenge is to generalize our methodologies to be applicable to larger systems. We plan to incorporate our methodology in the state-of-the-art ORCA electronic structure program, developed in the group of Frank Neese at MPI Mulheim an der Ruhr, and to capitalize on local correlation, in particular pair natural orbital techniques, which have been applied to systems as large as 50-100 atoms. In addition ORCA allows us to conveniently incorporate relativistic effects, in particular spin-orbit coupling, and this is a vital ingredient to simulate important spectroscopic properties. ORCA will be generalized to compute vibronic model parameters, while simulation of non-adiabatic dynamics is pursued employing the widely used Multiconfiguration Time-Dependent Hartree (MCTDH) package, developed in the Meyer group in Heidelberg, Germany.

为了详细了解复杂反应中的分子结构，例如在生物环境中，能够解释各种光谱测量是至关重要的。对于涉及多个过渡金属原子的系统，可行的光谱包括共振拉曼光谱、紫外-可见吸收光谱、圆二色光谱、磁圆二色光谱、电子顺磁共振光谱、x射线近边吸收光谱、x射线发射光谱、穆斯堡尔光谱、XPS光谱、核磁共振光谱和各种时间分辨泵浦探测技术。光谱的解释是一个复杂的过程，目前通常是基于与已知光谱的相似度匹配，以及使用简单的模型。光谱的解释，也许更重要的是，光谱所暗示的系统的（结构）表征，可以得到可靠的第一原理理论模拟的极大帮助，这是本提案的主题。过去，我们已经开发了精确模拟小分子电子能谱的技术。关键因素包括从精确的耦合簇型电子结构计算中提取所谓的振动模型参数，以及使用非绝热量子波包动力学研究多表面上量子核运动的演化。关键的挑战是将我们的方法一般化以适用于更大的系统。我们计划将我们的方法纳入MPI Mulheim and der Ruhr的Frank Neese小组开发的最先进的ORCA电子结构程序中，并利用局部相关性，特别是对自然轨道技术，该技术已应用于50-100个原子大小的系统。此外，ORCA允许我们方便地纳入相对论效应，特别是自旋-轨道耦合，这是模拟重要光谱特性的重要组成部分。ORCA将被推广到计算振动模型参数，而非绝热动力学的模拟将采用德国海德堡Meyer团队开发的广泛使用的Multiconfiguration Time-Dependent Hartree （MCTDH）软件包。