Non-Statisticality, Selectivity and Phase Space Structure in Organic Reactions

这项拟议的研究是根据NSF/EPSRC 2011年化学提案征集提案提交的。我们的美国合作者是纽约伊萨卡康奈尔大学化学和化学生物学系的格雷戈里·S·埃兹拉教授。这项工作是对有机反应中非统计动力学的理论和计算探索，受最近的实验启发，以及它与多原子分子经典哈密顿模型中相空间结构的关系。这项研究的总体目标是发展一种相空间方法来理解并最终预测有机分子热反应的非统计动力学。这类反应是最近许多实验和理论工作的重点，这些工作令人信服地表明，对于越来越多的情况，用于预测速率、产物比、立体专一性和同位素效应的标准过渡态理论方法完全失败。这项研究将应用最近在应用动力系统理论(如规范型理论)中的重大理论和计算进展来研究多模分子的反应动力学和相空间结构，并探索非统计行为的动力学起源。单分子速率的间隙时间公式将被用来为非统计行为提供新的诊断方法。这些方法将被用于研究一些典型的情况：呈现反应路径分叉的体系中的分支比；包含双自由基中间体的名义上的周环反应中的立体专一性；发生在浅势壁上的反应中的非统计性和动态匹配。我们将研究浴模的影响，并最终探索此类体系的量子效应的本质。选择性的控制可以说是合成化学家面临的最重要的问题。了解控制选择性的因素对化工企业至关重要，拟议的工作开始开发使非经验反应设计成为现实所必需的基本数学框架。预计这项工作将为正在进行的有机反应机理解释范式的转变提供严格的动力学基础，因此将在理论化学领域产生相当大的影响。合作机构之间的年度博士后交流将确保参与该项目的同事在广泛的研究方法方面接受广泛的跨学科教育。特别是在化学动力学、动力学系统和有机反应机理研究的子领域之间将会有卓有成效的交叉，这是新一代化学研究人员所需要的。这个项目是一个独特的合作努力，横跨物理有机化学、理论反应动力学和应用动力学系统理论。它解决了具有巨大实践和理论重要性的有机反应中的反应性和选择性问题，同时利用了哈密顿动力学理论中最先进的方法和概念。这种协作努力提供的协同作用对于在理解反应动力学中这类重要问题方面取得全面进展至关重要。PI带来了不同背景和优势的组合，据我们所知，它们在物理有机化学中提出的问题上的应用是前所未有的。三个私人投资机构的互补技能和专门知识将形成一个平衡的“三足鼎立”的能力，以解决这些问题。

The proposed research is submitted under the NSF/EPSRC Chemistry Proposals 2011 call for proposals. Our US collaborator is Professor Gregory S. Ezra of the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York. This work is a theoretical and computational exploration of nonstatistical dynamics in organic reactions, motivated by recent experiments, and its relation to phase space structure in classical Hamiltonian models for polyatomic molecules. The overall aim of the research is the development of a phase space approach to understanding and ultimately predicting nonstatistical dynamics in thermal reactions of organic molecules. Such reactions have been the focus of much recent experimental and theoretical work, which has convincingly demonstrated that, for a growing number of cases, standard transition state theory approaches for prediction of rates, product ratios, stereospecificity and isotope effects fail completely. The proposed research will apply the significant recent theoretical and computational advances in applied dynamical systems theory (e.g., normal form theory) to study reaction dynamics and phase space structure in multimode molecules, and to probe the dynamical origins of nonstatistical behavior. The gap time formalism for unimolecular rates will be used to provide novel diagnostics for nonstatistical behavior.These methods will be applied to a investigate a number of representative cases: branching ratios in systems exhibiting reaction path bifurcation; stereospecificity in nominally pericyclic reactions involving diradical intermediates; nonstatisticality and dynamic matching in reactions occuring on shallow potential walls. The influence of bath modes will be studied and, ultimately, the nature of quantum effects for such systems will be explored.Control of selectivity is arguably the most important problem that synthetic chemists face. Understanding the factors that control selectivity is of essential importance to the chemical enterprise, and the proposed work begins to develop the fundamental mathematical framework that will be necessary to make non-empirical reaction design a reality. It is anticipated that the work will provide a rigorous dynamical foundation for the ongoing paradigm shift in the interpretation of organic reaction mechanisms, and so have considerable impact beyond the field of theoretical chemistry.Annual exchanges of postdocs between collaborating institutions will ensure that the coworkers involved in the project will receive a broad interdisciplinary education in a wide range of research methodologies. There will in particular be fruitful cross-fertilization between the subfields of chemical dynamics, dynamical systems, and the study of organic reaction mechanisms, as required for a new generation of researchers in chemistry.This project is a unique collaborative effort spanning the fields of physical organic chemistry, theoretical reaction dynamics and applied dynamicalsystems theory. It addresses problems of reactivity and selectivity in organic reactions that are of immense practical and theoretical importance, while exploiting state-of-the-art methodology and concepts from the theory of Hamiltonian dynamics. The synergy provided by such a collaborative effort is essential for full progress to be made in understanding this important class of problems in reaction dynamics. The PIs bring a combination ofdifferent backgrounds and strengths whose application to the proposed problems in physical organic chemistry is, as far as we know, unprecedented. The complementary skills and expertise of the three PIs will form a well-balanced ``tripod'' of capabilities for attacking these problems.