Theoretical Studies of Solvation and Reaction Dynamics in Polar and Nonpolar Solvents

卡内基梅隆大学的Hyung Kim在理论和计算化学计划的支持下，在各种溶液环境中开展溶剂化和化学反应以及相关电子光谱的理论研究，如偶极和非偶极溶剂。通过将空间色散结合到反应场理论中，并借助分子动力学(MD)模拟，Kim将构建一个精确的连续统理论来描述可极化、非偶极、四极溶剂(如苯)中的平衡和非平衡溶剂化作用。量子化学技术将应用于小分子的溶剂化和各种电荷移动过程，如在苯和其他四极溶剂中的MenShukin反应和激发态电子转移反应。在分子动力学、量子化学和连续介质理论的共同作用下，这项工作将首次系统地研究四极溶剂中的电荷移动反应，适当地考虑非平衡溶剂化和相关的溶质-溶剂电子结构变化。与此同时，截断绝热基组(TAB)溶剂的电子描述将被改进以研究水的凝聚相性质。具体地说，TAB公式将被扩展，以将范德华和库仑相互作用的成对非相加的多体特征纳入模拟。这将允许短距离和长距离的相互作用随着溶剂的配置和热力学条件的变化而波动。该方法将用于研究常温和超临界条件下的气液相平衡、溶剂化动力学、线性/非线性电子能谱以及离子在水中的输运。许多化学反应发生在由溶解在非反应性液体溶剂中的反应性溶质组成的凝聚相中。例如，水是一种对化学、生物化学和化学工程至关重要的溶剂。超临界水在技术上很重要，这项研究有助于提供有用的理论模型，这些模型可以对从根本上理解工业上显著的溶剂化效应产生长期影响。

Hyung Kim of Carnegie-Mellon University is supported by the Theoretical and Computational Chemistry Program to carry out theoretical studies of solvation and chemical reactions and related electronic spectroscopy in diversified solution environments, such as dipolar and non-dipolar solvents. By incorporating spatial dispersion into reaction field theory with the aid of molecular dynamics (MD) simulations, Kim will construct an accurate continuum theory to describe equilibrium and nonequilibrium solvation in polarizable, non-dipolar, quadrupolar solvents, such as benzene. Quantum chemistry techniques will be applied to solvation of small molecules and various charge-shift processes, such as Menshutkin and excited-state electron transfer reactions in benzene and other quadrupolar solvents. With the combined efforts of MD, quantum chemistry, and continuum theory, this effort will provide the first systematic study of charge-shift reactions in quadrupolar solvents with proper account of nonequilibrium solvation and associated solute-solvent electronic structure variations. In parallel with this effort, the truncated adiabatic basis-set (TAB) solvent electronic description will be improved to study the condensed-phase properties of water. Specifically, the TAB formulation will be extended to incorporate the pairwise-non additive, many-body character of both van der Waals and Coulombic interactions into the simulations. This is expected to allow the short- and long-range interactions to fluctuate with the solvent configurations and vary with the thermodynamic conditions. This method will be applied to study liquid-vapor phase equilibria, solvation dynamics, linear/nonlinear electronic spectroscopy, and ion transport in water under ambient and supercritical conditions. Many chemical reactions occur in condensed phases consisting of reacting solutes that are dissolved in nonreacting liquid solvents. Water, for example, is a solvent of vital interest to chemistry, biochemistry, and chemical engineering. Supercritical water is technologically important, and this research helps provide useful theoretical models that can have long-range impacts on the fundamental understanding of industrially significant solvation effects.