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

David Coker得到了理论和计算化学计划的资助，继续他的研究，开发半经典方法来处理凝聚相系统中的量子动力学。基于传播子的半经典表达式，将发展计算凝聚相量子系统中实时关联函数的新方法，并将其用于模拟溶液相系统，其中核干涉和隧道效应在决定溶液中的光谱、输运和其他动态溶质性质方面起着至关重要的作用。半经典方法使用传播子方法，使用一群加权的经典轨迹，每个轨迹乘以一个相位因子。时间关联函数包含这些传播子中的两个，因此包括两对相位加权的经典轨迹之间的干扰效应。将非绝热分子动力学和半经验电子结构相结合的方法推广到研究三碘阴离子在溶液中的光解离和复合动力学。由于大多数工业合成过程都发生在溶液中，因此重要的是进一步了解溶剂对溶剂化体系中基本化学过程的影响，包括分子传输、质子转移和电子激发。这一理论研究将有助于更好地理解溶液中化学反应的影响因素。

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.