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首页> 外文期刊>The Journal of Chemical Physics >VIBRATIONAL ANALYSES OF TRANS,TRANS-1,3,5,7-OCTATETRAENE AND ALL-TRANS-1 ,3,5,7,9-DECAPENTAENE BASED ON AB INITIO MOLECULAR ORBITAL CALCULATIONS AND OBSERVED INFRARED AND RAMAN SPECTRA
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VIBRATIONAL ANALYSES OF TRANS,TRANS-1,3,5,7-OCTATETRAENE AND ALL-TRANS-1 ,3,5,7,9-DECAPENTAENE BASED ON AB INITIO MOLECULAR ORBITAL CALCULATIONS AND OBSERVED INFRARED AND RAMAN SPECTRA

机译：基于从头算分子轨道计算和观察到的红外和拉曼光谱的反式，反式-1,3,5,7-辛三烯和全反式-1,3,5,7,9-十碳烯的振动分析

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Normal coordinate analyses are performed for trans, trans-1,3,5,7-octatetaene and all-trans-1,3,5,7,9-decapentaene on the basis of ab initio molecular orbital (MO) calculations and observed infrared and Raman spectra. The infrared and Raman spectra of all-trans-1,3,5,7,9-decapentaene are measured in this study. Ab initio MO calculations are carried out at the second-order Moller-Plesset perturbation (MP2) level with the 6-31G* basis set. The calculated force fields are scaled by using the scale factors determined to obtain good fits between the calculated and observed frequencies of trans-1,3,5-hexatriene. The calculated frequencies are in satisfactory agreement with the observed for all the modes of both octatetraene and decapentaene including the in-phase C=C stretches, for which the calculated frequencies at the Hartree-Fock (HF) level deviate considerably from the observed. It is concluded that good force fields of all-trans oligoenes can be obtained from ab initio MP2 calculations by use of the scale factors derived in this study. From the comparison of the force fields at the MP2/6-31G* and HF/6-31G* levels, it is clear that electron correlation has large effects not only on the absolute values of diagonal and off-diagonal force constants of the C=C and C-C stretches but also on the chain-length dependence of these force constants. Important features of the vibrational modes are also discussed. (C) 1995 American Institute of Physics. [References: 51]
机译：在从头算分子轨道（MO）计算和红外光谱的基础上，对反式，反式-1,3,5,7-辛烯和全反式1,3,5,7,9-癸烯进行正态坐标分析和拉曼光谱。在这项研究中测量了全反式1,3,5,7,9-十碳烯的红外和拉曼光谱。从头算MO的计算是在6-31G *基础集的二阶Moller-Plesset微扰（MP2）级别上进行的。通过使用确定的比例因子来缩放计算的力场，以获得反式1,3,5-己三烯的计算频率与观察到的频率之间的良好拟合。对于包括同相C = C拉伸在内的辛八烯和十碳四烯的所有模式，计算出的频率与观察到的结果令人满意，为此，在Hartree-Fock（HF）水平上计算出的频率与观察到的有很大差异。结论是，通过使用本研究得出的比例因子，可以从头算MP2计算中获得全反式齐聚物的良好力场。通过比较MP2 / 6-31G *和HF / 6-31G *处的力场，很明显电子相关不仅对C的对角和非对角力常数的绝对值有很大影响= C和CC拉伸，但也取决于这些力常数的链长依赖性。还讨论了振动模式的重要特征。 （C）1995年美国物理研究所。 [参考：51]

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