Quantum Chemistry Methods for Excited States at Liquid- and Solid-State Interfaces

俄亥俄州立大学的John M. Herbert教授获得了化学系化学理论、模型和计算方法项目的奖励，他开发了分子如何相互作用的分子级计算机模型。该研究涉及水滴表面的化学，水滴是大气化学反应的主要介质。这些研究还研究了半导体光催化剂的表面，这是进行“人工光合作用”的有前途的材料，即以化学键的形式储存太阳能。赫伯特教授发展了理论方法，结合激光光谱学中新兴的实验技术来表征复杂系统。赫伯特教授的理论计算回答了有关金属氧化物光催化剂效率极限的基本问题，以及表面水分子与内部水分子的化学反应性有何不同。作为这项工作的一部分，新开发的理论和计算工具将被纳入QChem软件包，该软件包广泛用于化学教育和高通量计算工作，如哈佛清洁能源项目和电解质基因组计划。此外，这项工作的一个关键部分是开发计算机程序之间的接口，该接口可以免费提供给超级计算机中心，超级计算机中心包括俄亥俄州的所有学院和大学（主要包括本科生和非博士）。（授予机构）通过俄亥俄超级计算机中心。这项工作将把新的软件工具交到执业化学家手中。赫伯特教授正在开发量子化学方法，可以描述复杂系统的激发态，特别关注界面现象。这些方法是“QM:QM”嵌入的例子，使用高级电子结构方法（相关波函数或混合密度泛函）来描述激发态，使用低级方法（周期密度泛函理论）来描述环境。考虑了两种类型的界面现象：空气/水界面上溶剂化电子的光化学产生，其光谱可以提供该界面结构的敏感分子探针；水分解感兴趣的过渡金属氧化物光催化剂，其目标是了解限制催化效率的极化子自捕获动力学。这项研究与新兴的光谱技术密切相关，包括使用液体微射流探测空气/水界面的表面敏感紫外光谱和研究光催化材料的载流子动力学的飞秒瞬态XUV光谱。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。

Professor John M. Herbert of The Ohio State University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop molecular-level computer models of how molecules interact with each other. The research addresses chemistry at the surface of water droplets, which are the primary medium of atmospheric chemical reactions. The studies also examine the surface of semiconductor photocatalysts that are promising materials to conduct “artificial photosynthesis”, that is, the storage of solar energy in chemical bonds. Professor Herbert develops theoretical methods that combine with emerging experimental techniques in laser spectroscopy to characterize complex systems. Professor Herbert’s theoretical calculations answer fundamental questions regarding the efficiency limits of metal oxide photocatalysts as well as how the chemical reactivity of surface water molecules differ from that of interior water molecules. New theoretical and computational tools developed as part of this work will be incorporated into the QChem software package, which is widely used in chemical education and in high-throughput computational efforts such as the Harvard Clean Energy Project and the Electrolyte Genome Project. Furthermore, a crucial part of this work is the development of an interface between computer programs that is made freely available to supercomputer centers, which includes all colleges and universities within Ohio (including primarily undergraduate and non-Ph.D.-granting institutions) through the Ohio Supercomputer Center. This work will put new software tools into the hands of practicing chemists. Professor Herbert is developing quantum chemistry methods that can describe excited states of complex systems, with specific focus on interfacial phenomena. These methods are examples of “QM:QM” embedding, using high-level electronic structure methods (correlated wave functions or hybrid density functionals) to describe excited states and lower-level methods (periodic density functional theory) to describe the environment. Two types of interfacial phenomena are considered: photochemical generation of solvated electrons at the air/water interface, whose spectroscopy may offer a sensitive molecular probe of the structure of that interface and transition metal oxide photocatalysts of interest for water splitting, where the goal is to understand the polaron self-trapping dynamics that limit catalytic efficiency. This research is closely aligned with emerging spectroscopic techniques, including surface-sensitive UV spectroscopy using liquid microjets to probe the air/water interface and femtosecond transient XUV spectroscopy to study charge-carrier dynamics of photocatalytic materials.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.