A benchmark dataset of 86 intermolecular interactions of neutrals, ions, radicals and radical ions with water and hydrogen sulfide
7 affiliations
- 1Department of Chemistry
- 2California
- 3Bay Area Environmental Research Institute
- 4Astrophysics Division
- 5NASA Ames Research Center
- 6Chemical Sciences Division
- 7Lawrence Berkeley National Laboratory
Abstract
Guiding the selection of modern density functional approximations (DFAs) for intermolecular interactions requires diverse benchmark assessments. This work reports the development of a new test set of 86 binary complexes formed between either H 2 O or H 2 S and 31 selected partner species, comprising 15 neutral closed-shell molecules, 7 neutral radicals, 4 closed-shell anions, 2 closed-shell cations, and 3 cation radicals. The radical complexes are susceptible to delocalization error, while the interaction strengths span weak to very strong. Benchmark results are obtained at the coupled cluster singles, doubles and perturbative triples, CCSD(T), level, extrapolated towards the complete basis set limit from augmented triple and quadruple zeta basis calculations. This data is used to assess 17 different density functionals, spanning rungs 2 through 5 of Jacob’s Ladder. In common with other benchmarks, we find that the best functional on each higher rung of Jacob’s Ladder improves over the rung below, consistent with the potential to reduce the delocalization error. Only one functional, the ωB97M(2) double hybrid, achieves an RMS error of less than 1 kcal/mol. The best-performing hybrid is the recently introduced COACH functional, which has an RMS error just below 2 kcal/mol, while the best-performing meta-GGA and GGA have RMS errors above 3 and 4 kcal/mol respectively. These errors are dominated by the complexes that involve radical ions or neutral radicals. While the best-performing functionals are useful, these results indicate that further progress is still needed to address the delocalization error in intermolecular interactions.
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BibTeX
@misc{tomann2026benchmark,
title = {{A benchmark dataset of 86 intermolecular interactions of neutrals, ions, radicals and radical ions with water and hydrogen sulfide}},
author = {Rebecca Tomann and Partha P. Bera and Martin Head-Gordon},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008618/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008618/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A benchmark dataset of 86 intermolecular interactions of neutrals, ions, radicals and radical ions with water and hydrogen sulfide
AU - Rebecca Tomann
AU - Partha P. Bera
AU - Martin Head-Gordon
PY - 2026
DA - 2026/09/10
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008618/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008618/v1
AB - Guiding the selection of modern density functional approximations (DFAs) for intermolecular interactions requires diverse benchmark assessments. This work reports the development of a new test set of 86 binary complexes formed between either H 2 O or H 2 S and 31 selected partner species, comprising 15 neutral closed-shell molecules, 7 neutral radicals, 4 closed-shell anions, 2 closed-shell cations, and 3 cation radicals. The radical complexes are susceptible to delocalization error, while the interaction strengths span weak to very strong. Benchmark results are obtained at the coupled cluster singles, doubles and perturbative triples, CCSD(T), level, extrapolated towards the complete basis set limit from augmented triple and quadruple zeta basis calculations. This data is used to assess 17 different density functionals, spanning rungs 2 through 5 of Jacob’s Ladder. In common with other benchmarks, we find that the best functional on each higher rung of Jacob’s Ladder improves over the rung below, consistent with the potential to reduce the delocalization error. Only one functional, the ωB97M(2) double hybrid, achieves an RMS error of less than 1 kcal/mol. The best-performing hybrid is the recently introduced COACH functional, which has an RMS error just below 2 kcal/mol, while the best-performing meta-GGA and GGA have RMS errors above 3 and 4 kcal/mol respectively. These errors are dominated by the complexes that involve radical ions or neutral radicals. While the best-performing functionals are useful, these results indicate that further progress is still needed to address the delocalization error in intermolecular interactions.
ER -