Exploring Electronic Response Properties of Molecules and Extended Systems using Theoretical Methods

该项目由化学学部化学结构、动力学和机理（CSDM-A）和化学理论、模型和计算方法（CTMC）项目资助，布法罗大学的Jochen Autschbach教授，纽约州立大学和他的研究团队开发并应用基于量子理论的方法，以了解如何利用光（也称为电磁辐射）来确定分子的结构及其原子和电子的内部运动。Autschbach小组特别关注核磁共振（NMR）光谱和拉曼光谱。核磁共振波谱是医学诊断中使用的磁共振成像（MRI）技术的近亲，利用强磁场和射频光来揭示分子的结构。在拉曼光谱中，光（通常是可见光或紫外线波长的光）从分子中散射出来，散射光波长的细微变化可以为分子的振动运动及其整体结构提供线索。借助复杂的计算和计算机模拟，对这些分子性质的实验测量结果进行了预测和分析。这项研究促进了我们对分子结构和分子测量性质之间关系的理解，以及我们对电磁辐射与物质相互作用的一般理解。在这项调查中开发的理论方法和软件可供更大的科学家社区使用。此外，该研究项目为研究生和本科生提供了深入的培训，并为高中生提供了暑期实习的机会。项目的合作性质增强了学生的体验：虽然PI实验室的研究本质上是理论和计算的，但它是在与包括材料科学和催化在内的各个领域的实验研究人员合作的背景下进行的。所讨论的分子性质是在光谱或光学测量中观察到的，对了解分子的结构和功能具有很高的实际重要性。PI提供的理论支持对于建立和完善潜在的结构-性质关系至关重要。具体来说，感兴趣的性质决定了分子的核磁共振（NMR）和光学活性。该项目的理论研究重点是固态核磁共振参数、核磁共振弛豫现象以及自然电子和振动光学活性的结构和电子起源。此外，还探讨了化学和物理环境对这些分子性质的影响。核磁共振弛豫包含有关化学系统的动力学和特征相关时间的丰富信息。PI用ab-initio（从第一性原理）分子动力学模拟来研究弛豫，这使得研究包含元素周期表中所有元素的系统成为可能。该项目的光学活性相关部分侧重于拉曼振动光学活性中的共振效应，即当拉曼激光波长与电子激发波长重合时，以及圆偏振发光。计算固态核磁共振参数进行学习如何他们可能揭示未知结构的化学催化剂。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project funded by the Chemical Structure, Dynamics, and Mechanisms (CSDM-A) and Chemical Theory, Models and Computational Methods (CTMC) Programs of the Chemistry Division, Professor Jochen Autschbach of the University at Buffalo, State University of New York and his research team develop and apply quantum theory-based methods in order to learn how light (also known as electromagnetic radiation) can be used to determine the structure of molecules and the internal motions of their atoms and electrons. The Autschbach group is focusing specifically on nuclear magnetic resonance (NMR) spectroscopy and Raman spectroscopy. NMR spectroscopy is a cousin of the magnetic resonance imaging (MRI) technology used in medical diagnostics, and utilizes strong magnetic fields and radio-frequency light to reveal the structure of molecules. In Raman spectroscopy, light (often of visible or ultraviolet wavelengths) is scattered off molecules, and slight changes in the wavelength of the scattered light can provide clues to the vibrational motions of molecules and their overall structure. With the help of sophisticated calculations and computer simulations, the outcome of experimental measurements of these molecular properties are predicted and analyzed. This research advances our understanding of the relationships between molecular structure and measured properties of molecules, as well as our general understanding of the interaction of electromagnetic radiation and matter. Theoretical methods and software developed during this investigation are made available to the larger community of scientists. In addition, this research project provides in-depth training of graduate and undergraduate students, as well as opportunities for summer internships of high-school students. The student experience is enhanced by the collaborative nature of the project: While the research in the PI's laboratory is theoretical and computational in nature, it is carried out in the context of collaborations with experimental researchers from a variety of fields including materials science and catalysis. The molecular properties in question are observed in spectroscopic or optical measurements and of high practical importance to learn about the structures and functions of molecules. The theoretical support provided by the PI is crucial in order to establish and refine the underlying structure-property relationships. Specifically, the properties of interest determine the nuclear magnetic resonance (NMR) and the optical activity of molecules. The theoretical efforts of the project focus specifically on solid-state NMR parameters, NMR relaxation phenomena, and the structural and electronic origins of natural electronic and vibrational optical activity. In addition, the influence of the chemical and physical environment on these molecular properties is explored. NMR relaxation contains a wealth of information about the dynamics and characteristic correlation times of a chemical system. The PI studies the relaxation with ab-initio (from first principles) molecular dynamics simulations, which makes it possible to investigate systems containing elements from all across the periodic table. The optical activity-related part of the project focuses on resonance-effects in Raman vibrational optical activity, that is, when the Raman laser wavelength coincides with an electronic excitation wavelength, and on circularly polarized luminescence. Calculations of solid-state NMR parameters are undertaken to learn how they may reveal the unknown structures of chemical catalysts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.