Ab Initio Study on Phenylacetylene in S1 and S2
Ab Initio Study on Phenylacetylene in S1 and S2
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S1 和 S2 中苯乙炔的从头算研究
DOI：
10.1021/jp0355253
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发表时间：
2003
影响因子：
2.9
通讯作者：
Yasunori Hasebe
中科院分区：
文献类型：
--
作者：
Yoshiaki Amatatsu;Yasunori Hasebe
采用从头算完全活性空间自洽场（CASSCF）和二阶多参考Moller-Plesset（MRMP 2）方法研究了苯乙炔（PA）分子S 0、S1和S2的电子结构. PA在S 0和S1中的稳定结构均被优化为C2 v。S1中的稳定结构的特征是一个扩大的苯环，这是由苯环内的局部π−π* 激发引起的。另一方面，S2几何结构被优化为醌型结构，其中苯环的芳香性完全丧失。为了讨论从S2到S1的内转换，还确定了S2与S1的圆锥相交（S2/S1-CIX）。S_2/S_1-CIX的苯部分为醌型结构，乙炔部分为联烯型结构。计算结果很好地再现了转动常数和吸收谱的特征等实验结果。
The electronic structures of phenylacetylene (PA) in S0, S1, and S2 have been examined by means of ab initio complete active space self-consistent field (CASSCF) and the second-order multi-reference Moller−Plesset (MRMP2) calculations. The stable structures of PA in both S0 and S1 are optimized to be C2v. The stable structure in S1 is characterized as an enlarged benzene ring, which is caused by local π−π* excitation within the benzene ring. On the other hand, the S2 geometry is optimized to be a quinoid structure where the aromaticity of the benzene ring is completely lost. To discuss the internal conversion from S2 into S1, the conical intersection between S2 and S1 (S2/S1-CIX) has been also determined. The S2/S1-CIX is characterized as a quinoid structure in the benzene part and allene-like in the acetylene part. The present computational result well reproduces the experimental findings, such as the rotational constant and the feature of the absorption spectrum.