A Quantum Embedding Approach to Understanding Biological N2 Fixation

有了这个奖项，化学部门的生命过程化学项目将资助加州理工学院的托马斯·米勒博士研究生物和合成化学系统中的固氮作用。了解固氮（将氮气分解成更有用的形式）是对科学、工业和社会至关重要的挑战。固氮的主要途径是Haber-Bosch过程，产生氨（NH3）。除此之外，在固定氮方面几乎没有什么进展，尤其是在温和的温度和压力下。寻找在各种条件下运行的其他途径并了解它们是如何工作的，是化学科学中最难以捉摸的挑战之一。本研究采用了最近发展的计算量子化学方法来实现氮固定途径的详细表征。在这一过程中，研究生和博士后正在获得复杂系统的电子结构理论和反应动力学方面的专门培训。在这项研究中，新的理论方法正在被采用和发展，以提高计算可获得的准确性和效率。这个项目被整合到一个向高中学生和高中科学教师介绍计算化学科学的推广计划中。本研究项目旨在通过生物和合成催化剂表征氮固定的重要催化途径和反应中间体。该研究方法应用了最近开发的量子嵌入方法，可以在大幅降低计算成本的情况下对过渡金属催化剂反应中心的电子波函数（如CCSD(T)或CASPT2）进行高级描述。该项目涉及使用这些强大的新理论方法来阐明单位点和双位点合成模型中氮还原的催化途径。此外，该项目还包括了对蛋白质和溶剂环境中氮酶femo辅助因子的全面研究。该项目解决了生物、无机和理论化学研究前沿的物理问题和方法挑战。该项目将对氮还原的催化途径产生关键的见解，对两种可在合成实验室中测试的模型复合物有明确的机制见解，以及对氮酶的全部复杂性进行表征和预测。此外，该项目与NSF的其他小分子（如H2和CO2）的催化活化相关的研究重点以及食品、能源和水系统的创新（infws）计划具有协同作用。

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Thomas Miller from the California Institute of Technology to investigate nitrogen fixation in biological and synthetic chemical systems. Understanding nitrogen fixation (breaking N2 into more useful forms) is a challenge of paramount scientific, industrial and societal importance. The predominant route for nitrogen fixation is the Haber-Bosch process, resulting in ammonia (NH3). Beyond this process few advances have been made to fix nitrogen, especially at mild temperatures and pressures. The search for other routes that operate under various conditions and understanding how they work are among the most elusive challenges in the chemical sciences. Recently developed computational quantum chemistry methods are employed in this research to achieve a detailed characterization of pathways involved in nitrogen fixation. Throughout this pursuit graduate students and postdoctoral fellows are acquiring specialized training in electronic structure theory and reaction dynamics of complex systems. New theoretical methods to advance the accuracy and efficiency of what is computationally obtainable, are being employed and developed in this research. This project is integrated into an outreach program to introduce high school students and high school science teachers to the science of computational chemistry.This research project is undertaken to characterize important catalytic pathways and reaction intermediates for the fixation of nitrogen via biological and synthetic catalysts. The research approach applies recently developed quantum embedding methods that enable high-level descriptions of the electronic wave-functions (such as CCSD(T) or CASPT2) in the reaction center of transition metal catalysts at dramatically reduced computational costs. The project involves the use of these powerful new theoretical methods to elucidate the catalytic pathways for nitrogen reduction in both single-site and two-site synthetic models of the FeMo-cofactor. In addition the project incorporates full-scale studies of the nitrogenase FeMo-cofactor with protein and solvent environment. The project addresses physical questions and methodological challenges that are at the forefront of biological, inorganic, and theoretical chemistry research. The project will yield critical insights into the catalytic pathways for nitrogen reduction, clear mechanistic insights into both model complexes that are testable in the synthetic laboratory, as well as characterizations and predictions for the nitrogenase enzyme in its full complexity. Furthermore, the project is synergistic with NSF research priorities related to catalytic activation of other small molecules (such as H2 and CO2), as well as with the Innovations at the Nexus of Food, Energy and Water Systems (INFEWS) initiative.