Non-Born-Oppenheimer Effects between Electrons and Protons

伊利诺伊大学香槟分校的Sharon Hammes-Schiffer得到了化学部和高级网络基础设施部化学理论、模型和计算方法项目的支持，以开发高效和准确的计算方法，描述化学和生物系统中电子和质子的耦合运动。电子和质子之间的耦合在广泛的生物和化学过程中起着至关重要的作用，包括光合作用、呼吸作用和太阳能电池中的能量产生。很难开发出精确描述这种耦合的计算方法，因为电子和质子太轻，必须用量子力学来处理。经过广泛的评估和验证，这些计算方法将被纳入一个计算机程序，并将向公众开放。此外，这些计算方法将应用于与生物和化学相关的特定过程，以阐明决定这些过程的基本原理。Hammes-Schiffer教授和她的研究小组维护着一个网站，其中包含与这一主题相关的软件和教育工具。这个网站上提供的计算机程序、工具、演示和教程使广泛领域的科学家能够了解电子和质子的耦合运动。此外，该项目将通过更好地了解这一重要研究领域，促进技术和生物医学的进步。一个重要的例子是设计更有效的太阳能电池和其他替代的可再生能源。另一个例子是通过修饰依赖于电子和质子之间耦合的酶来设计更有效的药物。该项目的目标是开发新的理论和计算方法，以深入了解质子耦合电子转移(PCET)反应的基本原理。这些反应在广泛的生物和化学过程中起着至关重要的作用。要研究的具体问题包括核量子效应、氢隧道效应和非出生奥本海默效应的作用，这些效应被认为在PCET中具有重要意义。这些问题将使用核电子轨道(NEO)方法来探索，在NEO方法中，所有的电子和转移质子(S)都是用分子轨道方法或密度泛函理论在同一水平上进行量子力学处理的。这种方法使得能够计算PCET理论中的关键量，以确定速率和机制。它也适用于广泛的其他化学和生物体系。该项目的一个主要目标是开发算法来提高这种方法的计算效率，评估和验证该方法，并将近地天体代码移植到GamesS，这是一个向公众提供的通用量子化学软件包。近地天体方法受益于一般电子结构组件的其他部分的优化组件，部分近地天体代码将对其他科学家有用。这种软件开发实现了目前使用现有代码无法进行的计算。此外，还维护和加强了一个关于PCET的网站，以便向广大社区传达有用的信息。

Sharon Hammes-Schiffer of the University of Illinois at Urbana-Champaign is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry Division and the Division of Advanced Cyberinfrastructure to develop efficient and accurate computational methods that describe the coupled motion of electrons and protons in chemical and biological systems. The coupling between electrons and protons plays a vital role in a wide range of biological and chemical processes, including photosynthesis, respiration, and energy production in solar cells. It is difficult to develop computational approaches to accurately describe this coupling because electrons and protons are so light that they must be treated quantum mechanically. After extensive assessment and validation, these computational methods will be incorporated into a computer program that will be available to the public. Moreover, these computational methods will be applied to specific processes of biological and chemical relevance to elucidate the underlying fundamental principles that determine the processes. Professor Hammes-Schiffer and her research group maintain a web site that contains software and educational tools related to this topic. The computer programs, tools, demonstrations, and tutorials available on this web site enable scientists in a broad range of fields to learn about the coupled motion of electrons and protons. In addition, this project will facilitate technological and biomedical advances through a better understanding of this important research area. An important example is the design of more effective solar cells and other alternative, renewable energy sources. Another example is the design of more effective drugs through modification of enzymes that rely on the coupling between electrons and protons. The objective of this project is to develop new theoretical and computational approaches to provide insight into the underlying fundamental principles of proton-coupled electron transfer (PCET) reactions. These reactions play a vital role in a broad range of biological and chemical processes. The specific issues to be examined include the roles of nuclear quantum effects, hydrogen tunneling, and non-Born-Oppenheimer effects, which are thought to be significant in PCET. These issues will be explored using the nuclear-electronic orbital (NEO) approach, in which all electrons and the transferring proton(s) are treated quantum mechanically on the same level with molecular orbital methods or density functional theory. This approach enables the calculation of key quantities in PCET theories for determining rates and mechanisms. It is also applicable to a wide range of other chemical and biological systems. A major goal of this project is to develop algorithms to enhance the computational efficiency of this approach, assess and validate the methodology, and port the NEO code to GAMESS, a general quantum chemistry package available to the public. The NEO method benefits from the optimized components of other parts of the general electronic structure package, and portions of the NEO code will be useful to other scientists. This software development enables calculations that are not currently possible with existing codes. In addition, a web site on PCET is maintained and enhanced to convey useful information to the general community.