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

凯瑟琳·亨特博士得到了理论与计算化学项目的资助，研究分子偶极子和极化率的瞬态、碰撞引起的变化理论。这些研究将帮助光谱学家在亚皮秒时间尺度上探测流体的分子间动力学，这反过来将帮助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从观察到的线形中提取动态信息所需的分子偶极子和极化率的瞬态、碰撞引起的变化。对于具有轻微电荷重叠的相互作用分子，她计划使用新开发的极化密度理论进行计算，该理论解释了分子内极化率的分布和重叠阻尼，以及色散，高多极感应和局部电场的不均匀性。她将开发计算非局部响应张量的有效方法，包括非线性敏感性。她将找到这些张量的物理近似，并进行碰撞诱发性质的计算，这是重要的光谱。她计划通过改进的密度泛函方法或交换摄动理论来处理非加性交换极化。对于具有明显重叠的分子，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.