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arxiv: 2506.11590 · v2 · pith:LELCQ3E2new · submitted 2025-06-13 · ⚛️ physics.chem-ph · cond-mat.mtrl-sci· cond-mat.str-el· nucl-th· physics.comp-ph

The QUEST Database of Highly-Accurate Excitation Energies

Pierre-Fran\c{c}ois Loos , Martial Boggio-Pasqua , Aymeric Blondel , Filippo Lipparini , Denis Jacquemin This is my paper

Pith reviewed 2026-05-22 00:06 UTC · model grok-4.3

classification ⚛️ physics.chem-ph cond-mat.mtrl-scicond-mat.str-elnucl-thphysics.comp-ph
keywords excitation energiesvertical transitionsdatabasebenchmarkingquantum chemistryfull configuration interactiondouble excitationsRydberg states
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The pith

The QUEST database provides 1489 vertical transition energies within 0.05 eV of full configuration interaction for many molecules.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper introduces the QUEST database, which collects theoretical best estimates of vertical transition energies for 1489 excited states across a range of molecules containing up to 16 non-hydrogen atoms. These estimates cover valence and Rydberg transitions as well as states with double-excitation character, and most are considered chemically accurate because they fall within ±0.05 eV of the FCI/aug-cc-pVTZ reference. A sympathetic reader would care because such a reliable set of reference values allows for fair and balanced testing of different computational methods used in quantum chemistry to predict excited states. The paper also reports benchmarks for several wavefunction approaches using this data.

Core claim

The QUEST database includes 1489 aug-cc-pVTZ vertical transition energies for singlets, doublets, triplets, and quartets in molecules from 1 to 16 non-hydrogen atoms, with the vast majority deemed chemically accurate as they lie within ±0.05 eV of the corresponding FCI estimate.

What carries the argument

The QUEST database of highly-accurate excitation energies, constructed from theoretical best estimates benchmarked to full configuration interaction calculations in the aug-cc-pVTZ basis.

If this is right

  • Single- and multi-reference wavefunction methods can be systematically assessed for their accuracy on excited-state calculations.
  • The database facilitates the development of new methods by providing references for challenging double-excitation states.
  • Extensive supporting information allows users to test additional models beyond those benchmarked in the paper.
  • Both valence and Rydberg transitions are covered, enabling comprehensive performance evaluations.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Such a database could become a standard reference for validating machine learning potentials in photochemistry.
  • Extending the database to larger systems or different properties might reveal new trends in method performance.
  • Experimental spectroscopists could use these values to help assign peaks in complex spectra.

Load-bearing premise

The best estimates for systems too large for full FCI calculations do not introduce systematic errors larger than the 0.05 eV tolerance.

What would settle it

A new full configuration interaction calculation on one of the larger molecules in the database that deviates by more than 0.05 eV from the reported theoretical best estimate.

Figures

Figures reproduced from arXiv: 2506.11590 by Aymeric Blondel, Denis Jacquemin, Filippo Lipparini, Martial Boggio-Pasqua, Pierre-Fran\c{c}ois Loos.

Figure 1
Figure 1. Figure 1: Differences between the CCSDT/6-31+G(d) (top) or [PITH_FULL_IMAGE:figures/full_fig_p007_1.png] view at source ↗
Figure 4
Figure 4. Figure 4: Distribution of deviations from AVTZ VTEs obtained [PITH_FULL_IMAGE:figures/full_fig_p008_4.png] view at source ↗
Figure 3
Figure 3. Figure 3: Error distributions relative to AVTZ VTEs obtained [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: Distribution of deviations from AVTZ VTEs using 6- [PITH_FULL_IMAGE:figures/full_fig_p009_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Distribution of the errors on VTEs for various levels of theory using stacked histograms and considering all data from the [PITH_FULL_IMAGE:figures/full_fig_p012_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Distribution of the errors on VTEs for various levels of theory using stacked histograms and considering all data from the [PITH_FULL_IMAGE:figures/full_fig_p014_7.png] view at source ↗
read the original 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.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The manuscript presents the QUEST database of 1489 aug-cc-pVTZ vertical transition energies (VTEs) for molecules with 1–16 non-hydrogen atoms. The set comprises 731 singlets, 233 doublets, 461 triplets and 64 quartets, covering valence and Rydberg transitions with emphasis on states of partial or genuine double-excitation character. The central claim is that the vast majority of the reported theoretical best estimates lie within ±0.05 eV of the corresponding FCI/aug-cc-pVTZ values, thereby providing chemically accurate reference data for benchmarking single- and multi-reference excited-state methods. Supporting data and analysis tools are made available via a GitHub repository.

Significance. If the accuracy claim holds, QUEST would constitute a substantial resource for the excited-state community by supplying a large, balanced test set that includes difficult double-excitation cases. The public release of the full dataset together with analysis scripts on GitHub is a clear strength that supports reproducibility and enables independent testing of other models.

major comments (1)
  1. [Theoretical best estimates / composite protocols] Section describing the construction of theoretical best estimates: for the subset of molecules (1–16 non-H atoms) where full FCI is intractable, composite protocols (CCSDT(Q), extrapolated EOM-CCSDT, basis-set corrections) are substituted. No direct numerical comparison of these protocols against actual FCI/aug-cc-pVTZ is reported for any system larger than the FCI-feasible cases. Because the ±0.05 eV tolerance is the load-bearing criterion for the “chemically accurate” label applied to the majority of the 1489 entries, the absence of such validation leaves the central claim unverified, especially for Rydberg and double-excitation states.
minor comments (2)
  1. [Abstract / Introduction] The abstract and introduction would benefit from an explicit statement of how many entries rely on composite protocols versus direct FCI, together with a table summarizing the error statistics for the FCI-feasible subset.
  2. [Computational details] Notation for the various composite schemes should be standardized and cross-referenced to the supporting information so that readers can reproduce the exact extrapolation formulas used.

Simulated Author's Rebuttal

1 responses · 1 unresolved

We thank the referee for their positive assessment of the QUEST database and for the constructive major comment regarding the validation of our theoretical best estimates. We address the point in detail below.

read point-by-point responses

  1. Referee: Section describing the construction of theoretical best estimates: for the subset of molecules (1–16 non-H atoms) where full FCI is intractable, composite protocols (CCSDT(Q), extrapolated EOM-CCSDT, basis-set corrections) are substituted. No direct numerical comparison of these protocols against actual FCI/aug-cc-pVTZ is reported for any system larger than the FCI-feasible cases. Because the ±0.05 eV tolerance is the load-bearing criterion for the “chemically accurate” label applied to the majority of the 1489 entries, the absence of such validation leaves the central claim unverified, especially for Rydberg and double-excitation states.

    Authors: The referee correctly identifies that direct FCI/aug-cc-pVTZ comparisons can only be performed for the smaller molecules where such calculations are feasible. In the manuscript and supporting information, we have already benchmarked the composite protocols (including CCSDT(Q) and extrapolated EOM-CCSDT with basis-set corrections) against full FCI/aug-cc-pVTZ on all accessible systems, encompassing valence, Rydberg, and double-excitation states. These benchmarks confirm that the composites reproduce FCI values within the ±0.05 eV threshold for the large majority of cases. For the larger molecules (where FCI is intractable), we apply the identical protocols and base the uncertainty estimate on the observed performance on the FCI-feasible subset together with explicit convergence tests in basis set and correlation treatment. We agree that the manuscript would benefit from a clearer, more prominent presentation of this validation. We will therefore revise the relevant section to add a dedicated discussion of the composite-protocol validation, including a summary table of mean absolute deviations from FCI broken down by transition type (valence/Rydberg/double excitation) for the FCI-accessible molecules. revision: partial

standing simulated objections not resolved
  • Direct numerical comparison of the composite protocols against FCI/aug-cc-pVTZ for any molecule larger than the FCI-feasible cases (by definition intractable).

Circularity Check

0 steps flagged

No circularity: database compiles direct high-level computations without self-referential reductions

full rationale

The paper assembles a database of vertical transition energies via explicit FCI/aug-cc-pVTZ calculations where feasible and established composite protocols (e.g., CCSDT(Q) extrapolations) otherwise. These are first-principles evaluations benchmarked against external FCI results on the same basis set for smaller systems; no equations, parameters, or accuracy tolerances are defined in terms of the reported values themselves, nor do any predictions reduce to fitted inputs or self-citations by construction. The work is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The database rests on the assumption that FCI in the aug-cc-pVTZ basis provides a reliable reference for vertical transition energies and that best-estimate protocols for larger molecules preserve chemical accuracy.

axioms (1)
  • standard math Full configuration interaction in a finite basis set yields the exact energy for that basis.
    Invoked when stating that values are within 0.05 eV of the FCI/aug-cc-pVTZ estimate.

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