CAREER: Quantum Embedding of Wave-Function Methods as Path to High-Accuracy Thermochemistry in Heterogeneous Catalysis

宾夕法尼亚州立大学的Gerald Knizia得到了化学理论、模型和计算方法项目的支持，以开发一种准确和高效的多相催化理论方法。重点是在坚硬的表面上发生的反应，例如充当催化剂的金属。催化剂被用于家用产品和几乎所有工业化学品的生产，因为它们有助于加快化学合成。全球工业部门能源消耗的近25%是由于仅基础化学品和燃料的催化生产！通过计算分析对最小规模的化学反应过程进行合理的微观理解，可以大大有助于开发新的催化剂或改进现有的催化剂。然而，一个关键的挑战是，目前适用于表面反应的计算方法不够准确，不足以可靠地识别许多相互竞争的反应途径中的哪些实际上正在发生。这项研究通过使用小分子理论化学中的高精度计算方法来解决这一挑战，用于现实表面催化的复杂环境中。研究活动与针对高年级本科生和即将入学的研究生的教育方法相结合。教育活动的目标是帮助这些学生熟练使用计算技术。这项研究的更广泛的技术影响可能会导致工业流程的改善(例如，减少浪费、提高能源效率、减少对进口贵金属的依赖等)，从而有助于美国的独立经济。这些教育材料将向所有人提供，可能会为贫困但聪明的学生提供获得教育资源的机会，为学习强大的计算技术提供一个起点。具体地说，这项研究的目标是开发基于波函数的电子结构方法，这种方法具有足够的精度(相对能量~1kcal/mol)，允许在硬材料(如目前的工业多相催化剂)表面进行明确的热化学计算。首先，基于密度矩阵嵌入理论(DMET)，提出了一个合适的量子嵌入框架。该方法专门用于嵌入单个目标片段。这允许热化学波函数方法所需的偏振函数，并便于引入快速Kohn-Sham DFT来描述环境的平均场。其次，将开发高精度的局部耦合聚类法，该方法能够在存在嵌入的情况下使用。第三，前两个步骤中的技术将进行调整，通过从理想的块体/表面系统施加固定边界条件(而不是将周期性边界条件施加于目标系统本身)，将耦合到实际的周期性表面系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Gerald Knizia of Pennsylvania State University is supported by an award from the Chemical Theory, Models and Computational Methods program to develop an accurate and efficient theoretical approach to heterogenous catalysis. The focus is on reactions that take place on a hard surface, such as a metal, which acts as a catalyst. Catalysts are used in the production of household products and almost all industrial chemicals as they help speed up the chemical synthesis. Almost 25% of the global industrial-sector energy consumption is due to the catalytic production of basic chemicals and fuels alone! A sound microscopic understanding of the processes of chemical reactions at the smallest scale, obtained by computational analysis, could help substantially in developing new catalysts or improving existing ones. However, a key challenge is that the present computational methods applicable to surface reactions are not accurate enough to reliably identify which of the many competing reaction pathways are actually taking place in reality. This research addresses this challenge by enabling the use of high-accuracy computational methods from small-molecule theoretical chemistry, for use in the complex environments of realistic catalysis at surfaces. The research activities are integrated with an educational approach aimed at senior undergraduate and incoming graduate students. The goal of the educational activities is to help these students become proficient users of computational techniques. The broader technical impacts of the research may result in improvement in industrial processes (e.g., reducing waste, increasing energy efficiency, reducing dependence on imported precious metals, etc.), and thereby contribute to the economy of independence of the US. The educational materials will be made available to everyone, and may provide disadvantaged but bright students with poor access to educational resources with a starting point for learning powerful computing techniques. Concretely, the research targets the development of wave-function based electronic structure methods which have sufficient accuracy (~1 kcal/mol in relative energies) to allow for definitive thermochemical calculations on the surfaces of hard materials, such as current industrial heterogeneous catalysts. First, a suitable quantum embedding framework, based on the Density Matrix Embedding Theory (DMET) is developed. The method is specialized for embedding a single target fragment. This allows the polarization functions needed by thermochemical wave function methods and facilitates to be introduced using fast Kohn-Sham DFT for the mean-field description of the environment. Second, high-accuracy local coupled cluster methods will be developed which are capable of being used in the presence of the embedding. Third, the techniques from the first two steps will be adjusted to incorporate a coupling to an actual periodic surface system via imposing fixed boundary condition from ideal bulk/surface systems (as opposed to imposing periodic boundary conditions on the target system itself).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.