Comparison of ground and excited state polarizabilities of thiophene, cyclopentadiene, and fulvene oligomers and their cyano substituted derivatives - Ab initio study
Comparison of ground and excited state polarizabilities of thiophene, cyclopentadiene, and fulvene oligomers and their cyano substituted derivatives - Ab initio study
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DOI：
10.1002/polb.21190
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发表时间：
2007-08-01
影响因子：
--
通讯作者：
Lagowski, Jolanta B.
中科院分区：
文献类型：
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作者：
Ferdous, Sultana;Lagowski, Jolanta B.
分别用限制性Hartree-Fock(RHF)方法和组态相互作用单分子(CIS)方法，在3-21G*基组下，对噻吩基、富烯基和环戊二烯基导电性低聚物及其氰基衍生物的基态和激发态极化率进行了从头算研究。为了比较的目的，对于一些小的低聚物(单体和二聚体)，在极化率的计算中也使用了更高的基组(6-31G*，6-31+G*，aug-cc-pVTZ)。研究了极化率随齐聚物长度的变化趋势。对于所有体系，RHF极化率随着n的增大而增大(1.2-1.3)，当n小于7环或8环时，CIS极化率随n增大而增大(1.4-1.6)，对于较大的n，则随n近似线性增加。对于基于噻吩基的体系，我们还用RHF、密度泛函(DFT)和CIS理论(3-21G*基组)研究了其极化率与低聚物主链上的键长变化(BLA)的关系。对于噻吩二聚体，我们还进行了极化率与BLA的RHF/AUG-CC-pVTZ计算。我们发现，当BLA接近零时(无论是基态还是激发态)，极化率最大，这与最低激发能有关。在可能的情况下，与实验结果进行了比较。(C)2007年威利期刊公司。
Ab Initio study of the ground and excited state polarizabilities of thiophene, fulvene, and cyclopentadiene based conducting oligomers and their cyano derivatives have been performed using the restricted Hartree-Fock (RHF) and the configuration interaction singles (CIS) approaches, respectively, with 3-21G* basis set. For comparison purposes, for some small oligomers (monomers and dimers), higher basis sets (6-31G*, 6-31+G*, aug-cc-pVTZ) were also employed in the computations of polarizabilities. The trends in polarizability as a function of oligomer length were investigated. For all systems, the RHF polarizability increases as n(1.2-1.3) as n gets larger and the CIS polarizability increases as n(1.4-1.6) for n less than seven or eight rings and then increases approximately linearly with n for larger n. For the thiophene based systems the dependence of the polarizabillity on bond length alternation (BLA) along the backbone of the oligomers was also investigated using the RHF, density functional (DFT), and CIS theories (with 3-21G* basis set). For thiophene dimer, we also performed RHF/aug-cc-pVTZ calculations of polarizabilities versus BLA. We found that the polarizability is largest when BLA is near zero (for both ground and excited states), which correlates with the lowest excitation energy. Comparison with experimental results has been made where possible. (c) 2007 Wiley Periodicals, Inc.