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

物理化学计划中的这个项目侧重于 瞬态相互作用引起的理论测定 分子偶极和极化率随时间的变化 分子碰撞的规模。 其中， 相互作用的分子是轻微的，计算将基于 PI的非局部极化率密度模型， 对于可极化物质的分布， 分子。 该模型将被扩展到包括一个实际的 计算非局部非线性响应的方法。 的 将针对物理含量分析极化率密度， 碰撞引起的光谱学性质 被计算。 PI还将应用反应场理论， 发现色散对极化率的贡献 各向异性分子，并扩展了理论 频率相关的响应。 加入非加性的 交换极化的重叠是温和的，PI计划 进行密度泛函和交换微扰 计算;后者还包括电荷转移。 所需的单分子矩、磁化率和 短程对性质将由从头算确定 计算。 研究的代表物种包括 H2...氢气氮气N2，Ar.阿，阿...盐酸。 本研究是 重要的是它的光谱应用，因为显着 分子间动力学的信息可以从 碰撞诱导的吸收和散射光谱，如果这两个 碰撞诱导的偶极子和极化率已经被 确定为分子间距离的函数，相对 方向和振动频率。

This project in the physical chemistry program focuses on the theoretical determination of transient, interaction-induced changes in molecular dipoles and polarizabilities on the time scale of molecular collisions. Where overlap between the interacting molecules is slight, calculations will be based on the PI's nonlocal polarizability density model, which accounts for the distribution of polarizable matter throughout each molecule. The model will be extended to include a practical means of computing nonlocal, nonlinear response. The polarizability densities will be analyzed for physical content, and collision-induced properties of spectroscopic interest will be computed. The PI will also apply reaction field theory to find dispersion contributions to the polarizabilities of anisotropic molecules for the first time, and extend the theory to frequency-dependent response. To incorporate nonadditive exchange-polarization where overlap is moderate, the PI plans to perform density functional and exchange-perturbation calculations; the latter also include charge transfer. Required single-molecule moments, susceptibilities, and short-range pair properties will be determined by ab initio calculations. Representative species to be studied include H2...H2, N2...N2, Ar...Ar, and Ar...HCl. This research is important for its spectroscopic applications, since significant information on intermolecular dynamics can be extracted from collision-induced absorption and scattering spectra, if the two collision-induced dipoles and polarizabilities have been determined as functions of intermolecular distances, relative orientations, and vibrational frequency.