Semiclassical theory and simulation of vibrational energy relaxation and spectroscopic response functions in liquids

Eitan Geva教授由理论和计算化学计划支持，以了解液体溶液的量子动力学。 这就要求人们关注用于探测液体溶液的结构和动力学的量，并导致考虑两个主要问题。第一个问题需要一种新的方法来计算液体中的振动能弛豫速率常数。这些速率常数对量子动力学非常敏感，对于理解溶质-溶剂相互作用非常重要。 研究的第二个主要组成部分涉及光学响应函数的计算，这为探测溶剂化动力学提供了一种手段。 为了计算确定振动能弛豫率的一种新的方法，基于线性响应理论，正在开发和应用。这种方法的优点是它绕过了计算力-力相关函数的傅立叶变换的高频部分的需要。 该研究采用了一个理想化的模型，包括两个层次的生色团，非谐非极性溶剂，溶质-溶剂的相互作用，生色团的电子状态和偶极场之间的相互作用和物质。 现代计算化学的补充高级本科培训计划包括旨在汇集来自不同学科的计算科学家并促进跨部门合作。 这种方法的应用程序被施加到连续更复杂的二聚体/溶剂系统和中性homophosphoric中性heterophosphoric，最后带电homophosphoric的进展。 超快激光器的出现催生了多种新技术，可以直接询问溶剂化动力学。 这样的实验有效地允许一个实验解锁机制发生在飞秒的时间尺度，并应提供一种新的手段来理解生物学相关的过程。 然而，获取这些信息是以光子回波的形式出现的，这是自然界对莫尔斯码的类比，需要新的理论技术来正确地确定编码回波告诉我们什么。 这项研究的目标是开发和应用一种新的理论方法，解码出射光中包含的信息。 最初的应用程序是一类二聚体/溶剂系统，其中有大量的实验数据，并系统地包含所有的静电并发症，存在于非极性溶液中含有较大的分子。 正在开发一门高级本科课程，为未来的研究生提供理论物理化学所需的工具。

Professor Eitan Geva is supported by the Theoretical and Computational Chemistry Program to understand the quantum dynamics of liquid solutions. This requires one to focus on quantities that are used to probe the structure and dynamics of liquid solutions and leads to consideration of two primary problems. The first problem requires a new approach for calculating the vibrational energy relaxation rate constants in liquids. These rate constants are very sensitive to quantum dynamics and are important for understanding solute-solvent interactions. The second major component of the research deals with the calculation of optical response functions, which provide a means for probing solvation dynamics. To computationally determine vibrational energy relaxation rates a new method, based on linear response theory, is being developed and applied. The advantage of this method is it bypasses the need for calculating the high-frequency part of the Fourier transform of the force-force correlation function. The research employs an idealized model consisting of two-level chromophores, an anharmonic nonpolar solvent, solute-solvent interactions that vary with the chromophore electronic state and a dipolar interaction between the field and matter. A complementary senior-level undergraduate training program in modern computational chemistry is included that aims to bring together computational scientists from disparate disciplines and foster cross-departmental collaborations. Applications of this method are applied to successively more complex dimer/solvent systems and progress from neutral homonuclear diatomics to neutral heteronuclear diatomics and finally to charged homonuclear diatomics. The advent of ultrafast lasers has led to a multitude of novel techniques that enable the direct interrogation of solvation dynamics. Such experiments effectively allow one to experimentally unlock mechanisms occurring at the femtosecond time scale and should provide a new means for understanding biologically relevant processes. However, access to this information comes in the form of photon echoes, nature's analogy to the Morse code, and necessitates new theoretical techniques for correctly determining what the encoded echoes are telling us. The goal of this research is to develop and apply a new theoretical approach that decodes the information contained in the outgoing light. Initial applications are on a class of dimer/solvent systems for which there is a good amount of experimental data and which systematically contain all the electrostatic complications that are present in nonpolar solutions containing larger molecules. A senior level undergraduate course is being developed which will provide future graduate students with tools required for theoretical physical chemistry.