Post-CCSD(T) corrections to bond distances and vibrational frequencies: the power of Λ

2023/07/31 by Maciej Spiegel, Emmanouil Semidalas, Jan M. L. Martin +2 · 1 voice · 1 citation
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Advanced Chemical Physics Studies #Atmospheric Ozone and Climate #Spectroscopy and Laser Applications

paper · pdf · doi:10.1080/00268976.2023.2252114

openalex created_date 2023/07/29 · openalex publication_date 2023/09/01 · openalex updated_date 2026/08/01

Abstract

The importance of post-CCSD(T) corrections as high as CCSDTQ56 for ground-state spectroscopic constants (De, ωe, ωexe, and αe) has been surveyed for a sample of two dozen mostly heavy-atom diatomics spanning a broad range of static correlation strength. While CCSD(T) is known to be an unusually felicitous ‘Pauling point’ between accuracy and computational cost, performance leaves something to be desired for molecules with strong static correlation. We find CCSDT(Q)Λ to be the next ‘sweet spot’ up, of comparable or superior quality to the much more expensive CCSDTQ. A similar comparison applies to CCSDTQ(5)Λ vs. CCSDTQ5, while CCSDTQ5(6)Λ is essentially indistinguishable from CCSDTQ56. A composite of CCSD(T)-X2C/ACV5Z-X2C with [CCSDT(Q)Λ – CCSD(T)]/cc-pVTZ or even cc-pVDZ basis sets appears highly effective for computational vibrational spectroscopy. Unlike CCSDT(Q) which breaks down for the ozone vibrational frequencies, CCSDT(Q)Λ handles them gracefully.

Citations

• Configuration interaction calculations on the nitrogen molecule
• A diagnostic for determining the quality of single-reference electron correlation methods
• Coupled-cluster techniques for computational chemistry: The CFOUR program package

Cited by

• Harmonic and anharmonic vibrational computations for biomolecular building blocks: Benchmarking DFT and basis sets by theoretical and experimental IR spectrum of glycine conformers
• A new open-shell CCSDTQ implementation and its application to the basis set convergence of post-CCSDT(Q) corrections in computational thermochemistry

Discussions

• 🎉Good news! I’ve been awarded a 2024 Molecular Physics Early Career Researcher Prize for research done during my visit to Weizmann Institute of Science, supervised by Prof. Jan M. L. Martin: doi.or [bsky, 0 points, 0 comments]

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