QUEST Database of Highly-Accurate Excitation Energies

We report theoretical best estimates of vertical transition energies (VTEs) for a large number of excited states and molecules: the quest database. This database includes 1489 aug-cc-pVTZ VTEs (731 singlets, 233 doublets, 461 triplets, and 64 quartets) for both valence and Rydberg transitions occurring in molecules containing from 1 to 16 non-hydrogen atoms. Quest also includes a significant list of VTEs for states characterized by a partial or genuine double-excitation character, known to be particularly challenging for many computational methods. The vast majority of the reported values are deemed chemically accurate, that is, are within ±0.05 eV of the FCI/aug-cc-pVTZ estimate. This allows for a balanced assessment of the performance of popular excited-state methodologies. We report the results of such benchmarks for various single- and multireference wave function approaches, and provide extensive Supporting Information allowing testing of other models. All corresponding data associated with the quest database, along with analysis tools, can be found in the associated GitHub repository at the following URL: https://github.com/pfloos/QUESTDB.