QUEST Database of Highly-Accurate Excitation Energies

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Chemistry

Background:

• Accurate calculation of vertical transition energies (VTEs) is crucial for understanding molecular excited states.
• Challenging excited states, such as those with double-excitation character, require robust computational methods.
• Existing databases may lack comprehensive VTE data for a wide range of molecular systems and states.

Purpose of the Study:

• To establish a comprehensive database of theoretical best estimates for VTEs.
• To provide a benchmark dataset for evaluating excited-state computational methodologies.
• To facilitate the assessment of methods for challenging electronic configurations.

Main Methods:

• Generation of a large dataset of VTEs using high-level theoretical calculations (aug-cc-pVTZ basis set).
• Inclusion of singlet, doublet, triplet, and quartet states for valence and Rydberg transitions.
• Focus on molecules with 1 to 16 non-hydrogen atoms, including those with double-excitation character.

Main Results:

• The QUEST database contains 1489 aug-cc-pVTZ VTEs.
• The majority of VTEs are chemically accurate (within ±0.05 eV of FCI/aug-cc-pVTZ).
• Benchmarks of popular excited-state methodologies are reported, with data available for further testing.

Conclusions:

• The QUEST database serves as a valuable resource for computational chemistry research.
• It enables rigorous evaluation and development of methods for excited-state calculations.
• The availability of data and analysis tools promotes further advancements in the field.