The QUEST Database of Highly-Accurate Excitation Energies

TL;DR

The QUEST database provides highly accurate vertical transition energies for a wide range of molecules and states, enabling benchmarking of computational methods.

Contribution

This work introduces the QUEST database with extensive, chemically-accurate excitation energies for benchmarking excited-state computational methods.

Findings

Most VTEs are within ±0.05 eV of FCI/aug-cc-pVTZ estimates.

Benchmark results for various wavefunction approaches are reported.

Extensive data and analysis tools are available for testing other models.

Abstract

We report theoretical best estimates of vertical transition energies (VTEs) for a large number of excited states and molecules: the \textsc{quest} database. This database includes 1489 \emph{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. \textsc{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 $\pm0.05$ eV of the FCI/\emph{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 multi-reference wavefunction approaches, and provide extensive supporting information allowing testing of other models. All corresponding data associated with the \textsc{quest} database, along with analysis tools, can be found in the associated \textsc{GitHub} repository at the following URL: https://github.com/pfloos/QUESTDB.