Electronic Structure theories for Chemical Reactions

我们用分子的电子结构方法对化学反应进行了理论研究。本项目的主要课题是：（1）电子激发态的化学反应;（2）包括重金属和过渡金属原子的系统的反应;（3）开发以定量方式解释化学反应性的新轨道相互作用理论。对于第一个课题，我们发展了一种计算不同电子态间非绝热耦合元的方法，并将其应用于甲醛第一激发态的内转化速率常数的估算。该方法提供的速率常数与现有的实验结果吻合得很好。这项工作被认为是第一个非经验计算的内部转换率的多原子分子。在第二个主题中，我们建立了一个强有力的方法来设计新的化合物和控制反应性，使用从包含重元素的系统的初始计算获得的信息。进一步计算了过渡金属催化烯烃聚合反应的势能面，为揭示催化反应机理提供了重要信息。最后，我们提出了一个新的解释化学硬度的基础上轨道相互作用理论。

We have carried out theoretical studies of chemical reactions using electronic structure methods for molecules. The main subjects of the present project were (1) chemical reactions in the electronically excited states, (2) reactions of the systems including heavier and transition metal atoms, and (3) to develop new orbital interaction theories interpreting chemical reactivities in a quantitative manner. For the first subject, we developed a method for calculating the nonadiabatic coupling elements between different electronic states and applied it in estimating the internal conversion rate constants of the first excited state formaldehyde. This method provided the rate constants which are in good agreement with the available experimental findings. This work is regarded as the first nonempirical calculations of the internal conversion rate of polyatomic molecules. In the second subject, we established a powerful method to design new compounds and control the reactivities using the information obtained from ab inition calculations of systems including heavy elements. We further calculated the potential energy surfaces of the polymerization reactions of olefines with the aid of transition metal catalysis and obtained important informations to reveal the mechanism of catalytic reactions. Finally, we proposed a new interpretation of chemical hardness based on the orbital interaction theories.