MNDO calculations of stilbene potential energy properties relevant for the photoisomerization dynamics
MNDO calculations of stilbene potential energy properties relevant for the photoisomerization dynamics
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与光异构化动力学相关的二苯乙烯势能特性的 MNDO 计算
DOI：
10.1063/1.454402
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
K. Weitzel
中科院分区：
文献类型：
--
作者：
J. Troe;K. Weitzel
已经对二苯乙烯的低位电子激发态和电子基态进行了修正忽略微分重叠构型相互作用（MNDO-CI）计算。探讨了势能对围绕中心乙烯键的旋转角、该键的长度以及两个苯基的扭转角的依赖性。没有证据表明双激发“幻影态”非绝热参与光异构化动力学。相反，单激发 1 1B 态的计算特性支持围绕中心乙烯键绝热旋转到垂直构象，然后进行内部转换的机制。沿着这条路径似乎存在一个小的“CI 诱导”能量势垒，该能量势垒将通过多个坐标中的组合运动来克服。因此，出现了复杂的活化复合结构。
Modified neglect of differential overlap‐Configuration interaction (MNDO‐CI) calculations of the low‐lying electronically excited states and the electronic ground state of stilbene have been performed. The dependences of the potential energy on the angle of rotation around the central ethylene bond, on the length of this bond, and on the twist angle of the two phenyl groups are explored. There is no evidence for a nonadiabatic participation of the doubly excited ‘‘phantom state’’ in the photoisomerization dynamics. Instead, the calculated properties of the singly excited 1 1B state support a mechanism with adiabatic rotation around the central ethylene bond to the perpendicular conformation, followed by internal conversion. There appears to be a small ‘‘CI‐induced’’ energy barrier along this pathway which will be overcome by the combined motion in several coordinates. Therefore, a complicated activated complex structure arises.