电子转移的外电场效应──苯分子与苯正离子自由基间电子转移的从头算研究  

Effect of External Electric Field in Electron Transfer An Ab Initio Calculation for Electron Transfer Between Benzene and Benzene Cation Radical

作　　者：李象远[1] 唐星烁[1] 肖顺清[1] 赵新顺 何福城 

机构地区：[1]四川大学应用化学系,成都610065

出　　处：《高等学校化学学报》1999年第8期1280-1284,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金! (批准号 :2 970 610 4;2 95 73 112 );吉林大学理论化学计算国家重点实验室资助

摘　　要：基于半经典电子转移理论 ,结合量子化学计算 ,在 HF/DZP水平上 ,研究外电场作用下平行的苯分子 -苯正离子自由基体系 (C6 H4) + 2 的分子内电子转移问题 .在给体和受体几何构型优化的基础上 ,用线性反应坐标确定电子转移过渡态 ,分别用两态变分方法和基于 Koopmans定理的分子轨道跃迁能方法计算电子转移矩阵元 VAB,讨论了 VAB对给体和受体中心距 d的指数衰减关系 .取中心距为 0 .6 nm,研究了外电场对反应热的影响 ,计算得到在不同外电场强度下分子内气相电子转移的速率常数 k.Based on the semiclassical theory of electron transfer, quantum chemical calculations at HF/DZP level were performed for the study of intramolecular electron transfer between parallel benzene and benzene cation radical. After the geometric optimizations of the donor and the acceptor, a linear reaction coordinate \%ξ\% was introduced to determine the transition state. The variation principle applied to the two diabatic states and Koopmans theorem used in the calculation of molecular orbital transition energy, were invoked to evaluate the electron transfer matrix element \%V\%\-\{AB\}. The exponential falloff of \%V\%\-\{AB\} with increasing \%d\%, the distance between the center of the donor and that of the acceptor, was discussed. The influence of external electric field on the exothermicity of the electron transfer was investigated with \%d\%=0.6 nm, and then the rate constant \%k\% of the intramolecular gas\|phase electron transfer was estimated for different values of the external electric field strength.

关 键 词：电子转移 外电场 苯正离子自由基 苯分子 从头算 

分 类 号：O621.146[理学—有机化学] O625.11[理学—化学]