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.