New Insights into Excitation Energies of Organic Chromophores

Recent research has expanded the QUEST database, which focuses on highly accurate vertical transition energies, particularly for organic chromophores commonly used in dye chemistry. The study, titled "Reference CC3 Excitation Energies for Organic Chromophores: Benchmarking TD-DFT, BSE/GW and Wave Function Methods," was conducted by Iryna Knysh, Filippo Lipparini, Aymeric Blondel, Ivan Duchemin, Xavier Blase, Pierre-François Loos, and Denis Jacquemin. The authors computed singlet and triplet vertical transition energies at the CC3 level of theory, resulting in over 120 new excitation energies.

The research benchmarks various computational methods, including lower-order wave function approaches like ADC(2) and CC2, as well as time-dependent density-functional theory (TD-DFT). The findings indicate that CC2 and ADC(2.5) models are the most accurate among those tested, with CCSD not outperforming CC2. The study also highlights the effectiveness of several exchange-correlation functionals, achieving average deviations of approximately 0.20 eV or less. Notably, the performance of BSE calculations based on Kohn-Sham starting points was found to be particularly effective for singlet transitions.

This research is significant as it provides a more comprehensive understanding of excitation energies in organic chromophores, which are essential for various applications in materials science and photonics. The detailed benchmarking of computational methods can guide future studies and improve the accuracy of theoretical predictions in the field. The full paper can be accessed here.