5- and 6-Membered Rings: A Natural Orbital Functional Study
Ion Mitxelena1, Juan Felipe Huan Lew-Yee2,3,4, Mario Piris2,5,6
1Fisika Aplikatuko Departamentua, Vitoria-Gasteiz Ingenieritza Eskola, Euskal Herriko Unibertsitatea (EHU), Vitoria-Gasteiz, Euskadi 01006, Spain.
Journal of Chemical Theory and Computation
|March 6, 2026
Summary
The Global Natural Orbital Functional (GNOF) and its variant GNOFm accurately capture electron correlation in molecular rings. These functionals offer a reliable and robust approach for studying dynamic correlation effects in chemistry.
Area of Science:
- Computational Chemistry
- Quantum Chemistry
- Theoretical Chemistry
Background:
- Electron correlation is crucial for accurate molecular electronic structure.
- Existing methods often require approximations like perturbative corrections or active space selections.
- Dynamic correlation is a key factor in describing molecular systems.
Purpose of the Study:
- To evaluate the performance of the Global Natural Orbital Functional (GNOF) and its modified version (GNOFm).
- To assess their ability to capture dynamic correlation effects in molecular rings.
- To compare GNOF and GNOFm against the benchmark coupled cluster singles doubles with perturbative triples (CCSD(T)) method.
Main Methods:
- Utilized the Global Natural Orbital Functional (GNOF) and GNOFm.
- Calculated complete-basis-set limit correlation energies.
- Employed a set of twelve 5- and 6-membered molecular rings as a reference system.
- Used Dunning basis sets for calculations.
Main Results:
- Both GNOF and GNOFm provided a balanced and accurate description of dynamic correlation.
- GNOFm demonstrated minor but consistent improvements over the original GNOF.
- The functionals showed robustness and reliability across the tested molecular set.
- Results were benchmarked against CCSD(T) correlation energies.
Conclusions:
- The GNOF family of functionals reliably captures dynamic correlation effects.
- GNOF and GNOFm present a straightforward approach to electron correlation without complex approximations.
- These functionals are suitable for studying essential substructures in larger molecules.
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