Development of Semi-Classical Methods for Treating Quantum Dynamics in Condensed Phase Systems

David Coker获得了理论和计算化学项目的资助，继续研究凝聚态系统中处理量子动力学的半经典方法的发展。基于传播子的半经典表达式，将开发计算凝聚相量子系统实时相关函数的新方法，并将其应用于模型溶液相系统，其中核干涉和隧道效应在确定溶液中光谱、输运和其他动态溶质性质方面起着至关重要的作用。半经典方法采用一种传播子方法，使用一群加权的经典轨迹，每个轨迹乘以一个相位因子。时间相关函数包含两个这样的传播子，因此包含了相位加权经典轨迹对之间的干涉效应。将非绝热MD和半经验电子结构相结合的方法扩展到研究三碘阴离子在溶液中的光解和复合动力学。利用这种新的半经典方法，将探讨这种分子在溶液中的分子内振动的量子干涉效应。由于大多数工业合成过程都是在溶液中进行的，因此有必要进一步了解溶剂对溶剂化系统中基本化学过程的影响，包括分子传递、质子转移和电子激发。这一理论研究将使人们更好地了解影响溶液中化学反应的因素。

David Coker is supported by a grant from the Theoretical and Computational Chemistry Program to continue his research on the development of semiclassical methods for treating quantum dynamics in condensed phase systems. New methods for computing real time correlation functions in condensed phase quantum systems based on semiclassical expressions for the propagator will be developed and applied to model solution phase systems where nuclear interference and tunneling effects play a crucial role in determining spectroscopy, transport and other dynamical solute properties in solution. The semiclassical approach employs a propagator method using a swarm of weighted classical trajectories, each multiplied by a phase factor. The time correlation function contains two of these propagators and thus includes interference effects between pairs of phase weighted classical trajectories. Combined nonadiabatic MD and semiempirical electronic structure methods will be extended to study photodissociation and geminate recombination dynamics of triiodide anion in solution. Quantal interference effects in the intramolecular vibrations of this molecule in solution will be explored with this new semiclassical approach.Since most industrial synthetic processes occur in solution, it is important to gain an increased understanding of the influence that solvent has on fundamental chemical processes in solvated systems including molecular transport, proton transfer, and electronic excitation. This theoretical research will lead to an improved understanding of the factors which influence chemical reactions in solution.