An excited state coupled-cluster study on indigo dyes

In the present study, the domain-based pair natural orbital implementation of the similarity-transformed equation of motion method is employed to reproduce the vibrationally resolved absorption spectra of indigo dyes. After an initial investigation of multireference, basis set and implicit solvent effects, our calculated 0–0 transition energies are compared to a benchmark set of experimental absorption band maxima. It is established that the agreement between our method and experimental results is well below the desired 0.1 eV threshold in virtually all cases and that the shift in excitation energies upon chemical substitution is also well reproduced. Finally, the entire spectra of some of the main components of the Tyrian purple dye mixture are reproduced and it is found that our computed spectra match the experimental ones without an empirical shift.

本研究采用相似变换运动方程（similarity-transformed equation of motion）方法的基于域的对自然轨道（domain-based pair natural orbital）实现方案，复现靛蓝染料的振动分辨吸收光谱。在对多参考态（multireference）、基组（basis set）及隐式溶剂效应（implicit solvent effects）开展初步探究后，我们将计算得到的0-0跃迁能与一组实验吸收峰最大值基准数据集进行对比。研究证实，在几乎所有测试案例中，本方法与实验结果的吻合度均优于预设的0.1 eV阈值，且化学取代引发的激发能偏移也得到了良好复现。最后，我们复现了泰尔红紫（Tyrian purple）染料混合物中部分核心组分的完整光谱，发现计算所得光谱无需经验校正偏移即可与实验光谱完美匹配。