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Updated: Jul 18, 2026

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Convergence of third order correlation energy in atoms and molecules
Kalju Kahn1, Alex A Granovsky, Jozef Noga
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA. kalju@chem.ucsb.edu
Abstract:
We have investigated the convergence of third order correlation energy within the hierarchies of correlation consistent basis sets for helium, neon, and water, and for three stationary points of hydrogen peroxide. This analysis confirms that singlet pair energies converge much slower than triplet pair energies. In addition, singlet pair energies with (aug)-cc-pVDZ and (aug)-cc-pVTZ basis sets do not follow a converging trend and energies with three basis sets larger than aug-cc-pVTZ are generally required for reliable extrapolations of third order correlation energies, making so the explicitly correlated R12 calculations preferable.
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