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

卡内基梅隆大学的Hyung Kim在理论和计算化学项目的支持下，在多种溶液环境（如偶极和非偶极溶剂）中进行溶剂化和化学反应以及相关电子能谱的理论研究。通过在分子动力学（MD）模拟的帮助下将空间分散纳入反应场理论，Kim将构建一个精确的连续统理论来描述可极化、非偶极、四极性溶剂（如苯）中的平衡和非平衡溶剂化。量子化学技术将应用于小分子的溶剂化和各种电荷转移过程，如苯和其他四极性溶剂中的Menshutkin和激发态电子转移反应。在MD，量子化学和连续介质理论的共同努力下，这项工作将提供四极性溶剂中电荷转移反应的第一个系统研究，并适当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，截断绝热基集（TAB）溶剂电子描述将得到改进，以研究水的凝聚相性质。具体来说，TAB公式将被扩展，以将范德华和库仑相互作用的成对非加性，多体特征纳入模拟中。预计这将允许短期和长期相互作用随溶剂结构和热力学条件的变化而波动。该方法将应用于研究液-气相平衡，溶剂化动力学，线性/非线性电子能谱，以及环境和超临界条件下水中离子输运。许多化学反应发生在缩合相中，缩合相由溶解在不反应的液体溶剂中的反应溶质组成。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。超临界水在技术上是重要的，这项研究有助于提供有用的理论模型，可以对工业上重要的溶剂化效应的基本理解产生长期影响。

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.