烯酮光化二聚反应中非绝热跃迁的经典轨迹方法研究

STUDY ON NONADIABATIC TRANSITIONS IN PHOTO-DIMERIZATION OF KETENE BY USING CLASSICAL PATH METHOD

用经典轨迹方法，在π－ＣＩ势能面水平上计算了烯酮光化二聚的Ｈｕｃｋｅｌ途径和Ｍｏｂｉｕｓ途径的非绝热耦合项．根据非绝热跃迁几率的Ｌａｎｄａｕ－Ｚｅｎｅｒ公式，定义η＝ｌｎＰ（Ｈ）／ｌｎＰ（Ｍ）并用以讨论光化学反应的立体选择性．计算结果表明，光化学反应受两态Ｓ＿１和Ｓ＿０接近交叉处的能量间隙ΔＥ＿ｃ的控制，ΔＥ＿ｃ越小非绝热跃迁几率越大．

The nonadiabatic coupling terms for the photo-dimerization reactions of ktene havebeen calculated at the π-CI level by using the clastical path method.To discuss the stereoselectivitiesof the photoreactions a quantity η=lnP(H)/lnP(M)has been defined according to the Landau-Zener formula. The calculated results show that the energr gap at the near crossing point ΔE_c betweenS_1 and S_0 controls the reaction.