Guiglion Pierre, Zwijnenburg Martijn A
Department of Chemistry, University College London, 20 Gordon Street, WC1H 0AJ, UK.
Phys Chem Chem Phys. 2015 Jul 21;17(27):17854-63. doi: 10.1039/c5cp01916h.
We use a combination of Time-Dependent Density Functional Theory (TD-DFT) and approximate Coupled Cluster Theory (RI-CC2) to compare trends in the optical gap and fluorescence energies of ortho-, meta- and para-oligomers of phenylene. We find that RI-CC2 and TD-DFT calculations using three different commonly employed XC-potentials (B3LYP, BHLYP and CAM-B3LYP) generally give consistent predictions. Most importantly, the fluorescence energy of m-phenylene is predicted to be independent of oligomer length, the fluorescence energy of p-phenylene to decrease with oligomer length and that of o-phenylene to increase. The origins of these differences in behaviour between the different isomers are analysed and found to stem from a subtle combination of steric and electronic factors.
我们使用含时密度泛函理论（TD-DFT）和近似耦合簇理论（RI-CC2）相结合的方法，来比较亚苯基的邻位、间位和对位低聚物的光学能隙和荧光能量的趋势。我们发现，使用三种不同常用的XC势（B3LYP、BHLYP和CAM-B3LYP）进行的RI-CC2和TD-DFT计算通常给出一致的预测。最重要的是，预测间亚苯基的荧光能量与低聚物长度无关，对亚苯基的荧光能量随低聚物长度减小，而邻亚苯基的荧光能量则增加。分析了不同异构体之间这些行为差异的起源，发现其源于空间位阻和电子因素的微妙组合。
