Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
J Chem Phys. 2009 Nov 21;131(19):194306. doi: 10.1063/1.3263918.
Photoisomerization mechanism of azobenzene in the lowest excited state S(1)(n pi(*)) is investigated by ab initio molecular dynamics (AIMD) simulation with the RATTLE algorithm, based on the state-averaged complete active space self-consistent field method. AIMD simulations show that cis to trans isomerization occurs via two-step rotation mechanism, accompanying rotations of the central NN part and two phenyl rings, and this process can be classified into two types, namely, clockwise and counterclockwise rotation pathways. On the other hand, trans to cis isomerization occurs via conventional rotation pathway where two phenyl rings rotate around the NN bond. The quantum yields are calculated to be 0.45 and 0.28+/-0.14 for cis to trans and trans to cis photoisomerizations, respectively, which are in very good agreement with the corresponding experimental results.
通过基于态平均完全活性空间自洽场方法的 RATTLE 算法的从头算分子动力学 (AIMD) 模拟，研究了最低激发态 S(1)(n pi(*))中偶氮苯的光致异构化机制。AIMD 模拟表明，顺式到反式异构化通过两步旋转机制发生，伴随着中央 NN 部分和两个苯基环的旋转，这个过程可以分为两种类型，即顺时针和逆时针旋转途径。另一方面，反式到顺式异构化通过传统的旋转途径发生，其中两个苯基环围绕 NN 键旋转。计算得到的顺式到反式和反式到顺式光致异构化的量子产率分别为 0.45 和 0.28+/-0.14，与相应的实验结果非常吻合。
