Reaction dynamics of excited state molecules in solution

溶剂的电子极化在溶液分子动力学过程中起着重要的作用。我们提出了电荷响应核（CRK），它被定义为分子电子能量相对于作用在分子相互作用位点上的静电势的二阶导数，以表示溶液中溶质分子和溶剂分子中的电荷极化。CRK矩阵可以很容易地通过从头算分子轨道计算来计算。研究了电子极化对溶液中自由基扩散的影响。实验观察到，光引发的溶剂分子抽氢所产生的自由基的扩散常数大于母体分子的扩散常数。为了阐明那些实验。我们进行了吡嗪和吡嗪基自由基在甲醇中的分子动力学计算。采用RISM-SCF方法研究了溶剂波动对溶质电子激发能的影响。研究结果如下：(1)溶剂空间波动对水溶液中甲醛吸收光谱曲线的影响；(2)溶剂电子极化对丙酮和吡啶垂直激发能的影响；(3)苯腈电子激发引发溶剂介电松弛的RISM-SCF时效分析方法。为了估计溶质相互作用位点上静电势的波动来自溶剂的空间波动，我们利用由RISM-SCF计算得到的协方差矩阵假设为高斯分布，并根据高斯分布函数计算出静电势集合的溶质激发能分布。对溶剂振动的影响也进行了研究。利用CRK方法建立了电荷极化的RISM-SCF方法，该方法将溶质分子周围的溶剂电子极化纳入其中。以乙腈、氯仿、四氯化碳和二硫化碳等非极性极化分子为溶剂，考察了溶剂电子极化对溶质垂直激发能的影响。结果表明，溶剂电子极化对溶剂化位移的贡献与溶剂的衍射指数密切相关。结合溶剂弛豫动力学的线性响应理论，提出了一种随时间变化的RISM-SCF方法。讨论了水、甲醇和乙腈溶液中随时间变化的斯托克斯位移的差异。少

Electron polarization of solvent is known to play an important role in the dynamics of molecular processes in solution. We proposed the charge response kernel (CRK) which was defined as the second derivatives of molecular electronic energy with respect to the electrostatic potentials acting on the molecular interaction sites in order to represent the charge polarization in solute and solvent molecules in solution. The CRK matrix can be easily calculated by ab initio molecular orbital calculations. We examined the effect of electronic polarization on the diffusion of radical in solution. It has been experimentally observed that the diffusion constant of radical species generated by photo-initiated hydrogen abstraction from a solvent molecule is larger than that of the parent molecule. In order to elucidate those experiments. we carried out molecular dynamics calculations of pyrazine and pyrazinyl radical in methanol. We also studied the effect of solvent fluctuation on solute electronic … More excitation energies using the RISM-SCF method. The results were presented for (1) the solvent spacial fluctuation effect on the absorption spectral profile of formaldehyde in aqueous solution, (2) the solvent electronic polarization effect on the vertical excitation energies of acetone and pyridine, and (3) the time-dependent RISM-SCF approach to the dielectric relaxation of solvents initiated by the electronic excitation of benzonitrile. In order to estimate the fluctuation of electrostatic potential acting on the solute interaction sites coming from the solvent spacial fluctuation, we assumed a Gaussian distribution with the covariance matrix derived by RISM-SCF calculations and calculated the distribution of solute excitation energies with the set of electrostatic potentials generated according to the Gaussian distribution function. The contribution from solvent vibrations were also examined. The CRK method was utilized to develop the charge polarizable RISM-SCF method, which incorporate the solvent electronic polarization around the solute molecule. We took nonpolar polarizable molecules such as acetonitrile, chloroform, carbon tetrachloride and carbon disulfide as solvents in examining the solvent electronic poladzation effects on the solute vertical excitation energies. It was shown that the contribution of solvent electronic polarization to the solvation shifts was well related to the diffraction index of solvents. A time-dependent RISM-SCF method was further proposed by combining with the linear response theory for solvent relaxation dynamics. Difference in time-dependent Stokes shifts for water, methanol and acetonitrile solutions was discussed. Less