Theory of Transient, Collision-Induced Changes in Molecular Dipoles and Polarizabilities

凯瑟琳·亨特博士得到了理论和计算化学计划的资助，研究分子偶极和极化率的瞬时碰撞诱导变化理论。这些研究将帮助光谱学家在亚皮秒的时间尺度上探索流体的分子间动力学，这反过来将有助于他们阐明对化学反应至关重要的溶质-溶剂相互作用。亨特博士的理论工作将有助于确定分子偶极和极化率在碰撞诱导下的瞬时变化，这些变化是从观察到的线条形状中提取动力学信息所必需的。对于电荷略有重叠的相互作用分子，她计划使用一种新开发的极化密度理论进行计算，该理论解释了分子内的极化分布和重叠衰减，以及色散、更高的多极感应和局部电场中的不均匀。她将开发有效的方法来计算非局部响应张量，包括非线性极化率。她将找到这些张量的物理近似，并对碰撞诱导的性质进行计算，这些性质在光谱上是重要的。她计划通过改进的密度泛函方法或交换微扰理论来处理非加性交换极化。对于有明显重叠的分子，也将进行从头计算。

Dr. Katherine Hunt is supported by a grant from the Theoretical and Computational Chemistry Program to study the theory of transient, collision-induced changes in molecular dipoles and polarizabilities. These studies will help spectroscopists to probe intermolecular dynamics of fluids on subpicosecond time scales which in turn will help them to elucidate solute-solvent interactions critically important to chemical reactions. Dr. Hunt's theoretical work will help to determine transient, collision-induced changes in molecular dipoles and polarizabilities needed to extract dynamical information from observed line shapes. For interacting molecules with slight charge overlap, she plans to perform calculations using a newly developed polarizability density theory which accounts for the intramolecular distribution of polarizability and for overlap damping, as well as dispersion, higher-multipole induction, and nonuniformity in the local electric field. She will develop efficient methods for computing nonlocal response tensors, including nonlinear susceptibilities. She will find physically-based approximations to these tensors, and carry out calculations of collision-induced properties that are important spectroscopically. She plans to treat nonadditive exchange-polarization via a modified density-functional approach or exchange-perturbation theory. Ab initio calculations will also be carried out for molecules with appreciable overlap.