Resonance and Electronically Non-Adiabatic Effects in State-To-State Reaction Dynamics Using Massively Parallel Computers

在这个项目中，加州理工学院的库普曼教授得到了化学部理论和计算化学项目的支持。该项目涉及研究状态对状态化学反应动力学中的电子非绝热效应。所用的主要反应是氢氢与各种同位素变体之间的氢交换反应。其他被考虑的反应包括F-H2反应以及O-H2反应。将研究处理和合并多个电子表面和非绝热效应的各种方法。大规模并行超级计算机正在得到相当大的应用。人们特别注意“几何相”在影响这类反应的反应概率方面的作用。基本的双分子化学反应是复杂的具有重要技术意义的化学系统的基本步骤，如燃烧过程、大气化学、化学激光和等离子体反应堆。这些体系可能涉及许多步骤，这些步骤的试剂经常是短暂的，在许多情况下不能通过实验分离出来。在这种情况下，研究它们的横截面和速率在理论上是最好的，如果不是唯一可用的方法。这类研究还阐明了它们在分子水平上的细节，并导致了对它们如何发生的基本了解。在这项利用大规模并行计算机的计算研究中，提出了非常简单的气相化学反应的理论描述，例如氢原子和氢分子之间的化学反应，以及氧原子和氢分子之间的化学反应。

In this project Professor Kuppermann of the California Institute of Technology is being supported by the Theoretical and Computational Chemistry Program of the Chemistry Division. The project involves the study of electronic non-adiabatic effects in state-to-state chemical reaction dynamics. The primary reaction used is the hydrogen exchange reaction between H + H2 and various isotopic variants. Other reactions considered include the reaction of F + H2, as well as O + H2. Various ways of treating and incorporating multiple electronic surfaces and non-adiabatic effects will be investigated. Considerable use is being made of massively parallel supercomputers. Special attention is being placed on the role of the `geometric phase` in influencing the reaction probabilities for such reactions. Elementary bimolecular chemical reactions are the basic steps of complex technologically important chemical systems, such as combustion processes, atmospheric chemistry, chemical lasers, and plasma reactors. These systems may involve many steps whose reagents are very frequently short-lived and in many instances cannot be isolated experimentally. Studying their cross sections and rates theoretically constitutes in such cases the best, if not the only, available approach. Such studies also elucidate their molecular level details and lead to a fundamental understanding of how they occur. The theoretical description of very simple gas-phase chemical reactions such as those between a hydrogen atom and a hydrogen molecule, and oxygen atom and hydrogen molecule are being advanced in this computational study which makes use of massively parallel computers.