Molecular Electronic Structure Theory: Methods and Applications

Henry (Fritz) Schaeffer获得了化学学部化学理论、模型和计算方法项目的奖励，为量子化学开发了新的计算和理论方法。这个项目有助于理解原子、分子和气体、液体和固体相中的分子组合。这些是化学的基本组成部分，它们奠定了我们对从激光到超导体再到生化系统等材料的理解。科学中最重要的方程，薛定谔方程，是科学和工程领域新发现的关键，这些领域致力于对人类具有重要意义的进步。当人们说到薛定谔方程时，实际上每个不同的分子系统都有不同的薛定谔方程。这些方程对于广泛的、普遍的系统来说是极其复杂的。薛定谔方程的实际解需要对数学和物理的深刻掌握，以便推导出重要的新方法。Schaefer博士和他的研究团队在数学物理、算法设计和计算机科学的开发和应用方面表现出色，以实现这些目标。密度累积泛函理论是一种重要的新方法。该研究小组还将这些新方法应用于解决化学科学中的重要问题。他们在锰二氧化碳还原、钯催化剂、硅化学、氮化镓纳米管、CF3替代品SF5和PF4、碘簇和大气化学等方面的研究涉及到几个技术领域。这个项目的重点是发展新的理论和计算方法来理解和预测化学现象。更具体地说，Schaefer小组使用电子结构理论（量子化学）来创新、实施和应用新的方法来描述分子中的电子相关性，这是化学理论中最具挑战性的领域之一。本建议的重点是发展多参考密度累积理论（MRDCT）。MRDCT的建立涉及到新形式主义的轮廓，有效算法的设计，方法的仔细编码以及通过基准进行评估。新的和现有的理论方法的应用包括分子结构；光谱学（微波、红外、电子、拉曼）；势能面；能量;通过有机金属催化剂（通常涉及地球丰富的金属锰）的反应；钯催化C-H键活化和还原性消除；研究过硫化物（R1SSR2）和硫化物（R2SR4）之间具有重要生物学意义的一类反应；并与实验合作，朝着合成重要的新型主基团化学靶点的方向发展。这项研究更广泛的影响包括培养了大量有天赋的博士生（目前有16名博士生）。谢弗教授积极而成功地招募女性和少数族裔攻读博士学位。这些博士生（迄今为止有110名毕业，其中包括23名女性）几乎无一例外地在学术界、政府实验室和工业界从事了卓有成效的科学事业。谢弗的研究小组接触了当地小学、初中和高中的学生。Schaefer小组正在积极开发PSI4，这是一个免费的、开源的、全面的、广泛使用的量子化学计算机程序套件。对于科学家来说，在PSI4代码中添加新功能是特别容易的。

Henry (Fritz) Schaeffer is supported by an award from the Chemical Theory, Models and Computational Method program in the Division of Chemistry to develop new computational and theoretical approaches for quantum chemistry. This project contributes to the understanding of atoms, molecules, and molecular assemblies in the gas, liquid, and solid phases. These are the elementary components of the chemistry that underlies our understanding of materials from lasers to superconductors and on to biochemical systems. The most important equation in science, the Schrodinger Equation, is the key to new discoveries in science and engineering, areas dedicated to advances of importance to humankind. While one speaks of the Schrodinger Equation, in fact there is a different Schrodinger Equation for every different molecular system. These equations are extremely complicated for systems of broad, general interest. The practical solutions of the Schrodinger Equation require a profound mastery of both mathematics and physics to allow the derivation of important new methods. Dr. Schaefer and his research team excel in the development and application of mathematical physics, algorithm design, and computer science to achieve these goals. An important new method being developed is density cumulant functional theory. The research group also applies these new methods to the solution of important problems in the chemical sciences. Their research on manganese CO2 reduction, palladium catalysts, silicon chemistry, gallium nitride nanotubes, the CF3 substitutes SF5 and PF4, iodine clusters, and atmospheric chemistry, bears upon several areas of technological concern. This project focuses on the development of new theoretical and computational methods for the understanding and prediction of chemical phenomena. More specifically, the Schaefer group uses electronic structure theory (quantum chemistry) to innovate, implement, and apply new methods for the description of electron correlation in molecules, one of the most challenging areas of chemical theory. A emphasis of this proposal is the development of multi-reference density cumulant theory (MRDCT). The establishment of MRDCT involves the outline of the new formalism, design of effective algorithms, careful coding of the method, and assessment through benchmarks. Applications of new and existing theoretical methods include molecular architectures; spectroscopy (microwave, infrared, electronic, Raman); potential energy surfaces; energetics; reactions via organometallic catalysts (often involving the earth abundant metal manganese); palladium catalysis for C-H bond activation and reductive elimination; examination of the biologically important class of reactions between persulfides (R1SSR2) and sulfides (R2SR4); and collaborations with experiment toward the synthesis of critically important new main group chemistry targets. Broader impacts of the research include the education of a significant number of gifted Ph.D. students (16 in the group currently). Professor Schaefer aggressively and successfully recruits women and underrepresented minorities for their Ph.D. studies. These doctoral students (110 graduated to date, including 23 women) almost uniformly go on to highly fruitful scientific careers in academia, government laboratories, and industry. Schaefer's research group reaches out to local students in elementary, middle, and high schools. The Schaefer group is active in the development PSI4, a freely-available, open source, comprehensive, and widely used suite of quantum chemistry computer programs. It is especially easy for scientists to add new features to the PSI4 code.