Sutton Christopher, Yang Yang, Zhang Du, Yang Weitao
Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States.
Department of Physics , Duke University , Durham , North Carolina 27708 , United States.
J Phys Chem Lett. 2018 Jul 19;9(14):4029-4036. doi: 10.1021/acs.jpclett.8b01366. Epub 2018 Jul 6.
The 2A and 1B excited states of two prototypical π-conjugated compounds, polyacetylene and polydiacetylene, are investigated with the recently developed particle-particle random phase approximation (pp-RPA) method combined with the B3LYP functional. The polymer-limit transition energies are estimated as 1.38 and 1.72 eV for the 2A and 1B states, respectively, from an extrapolation of the computed excitation energies of model oligomers. These values increase to 1.95 and 2.24 eV for the same transitions when ground-state structures with ∼33% larger bond length alternation are adopted. Applying the pp-RPA to the vertical excitation energies in oligodiacetylene, the polymer-limit transition energies of the 2A and 1B states are computed to be 2.06 and 2.28 eV, respectively. These results are in good agreement with experimental values or theoretical best estimates, indicating that the pp-RPA method shows great promise for understanding many photophysical phenomena involving both single and double excitations.
采用最近开发的粒子-粒子随机相位近似（pp-RPA）方法并结合B3LYP泛函，对两种典型的π共轭化合物聚乙炔和聚二乙炔的2A和1B激发态进行了研究。通过对模型低聚物计算得到的激发能进行外推，聚合物极限跃迁能对于2A和1B态分别估计为1.38和1.72电子伏特。当采用键长交替约大33%的基态结构时，相同跃迁的这些值增加到1.95和2.24电子伏特。将pp-RPA应用于低聚二乙炔中的垂直激发能，计算得到2A和1B态的聚合物极限跃迁能分别为2.06和2.28电子伏特。这些结果与实验值或理论最佳估计值吻合良好，表明pp-RPA方法在理解涉及单重和双重激发的许多光物理现象方面显示出巨大潜力。
