Benchmarking the quadrupolar coupling tensor for chlorine to probe weak-bonding interactions

• Published in: Physical chemistry chemical physics : PCCP 2023-01, Vol.25 (3), p.242-2429
• Main Authors: Dohmen, Robin, Fedosov, Denis, Obenchain, Daniel A
• Format: Article
• Language: English
• Subjects: Bonding strength; Chlorine; Computing costs; Coupling (molecular); Density functional theory; Mathematical analysis; Molecular clusters; Optimization; Performance prediction; Quadrupole interaction; Quadrupoles; Quantum chemistry; Rotational spectra; Spectrum analysis; Tensors
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d2cp04067k

Rotational spectroscopy relies on quantum chemical calculations to interpret observed spectra. Among the most challenging molecules to assign are those with additional angular momenta coupling to the rotation, contributing to the complexity of the spectrum. This benchmark study of computational methods commonly used by rotational spectroscopists targets the nuclear quadrupole coupling constants of chlorine containing molecules and the geometry of its complexes and clusters. For each method, the quality of both structural and electronic parameter predictions is compared with the experimental values. Ab initio methods are found to perform best overall in predicting both the geometry of the complexes and the coupling constants of chlorine with moderate computational cost. This cost can be reduced by combining these methods with density functional theory structure optimization, which still yields adequate predictions. This work constitutes a first step in expanding Bailey's quadrupole coupling data set to encompass molecular clusters. [W. C. Bailey, Calculation of Nuclear Quadrupole Coupling Constants in Gaseous State Molecule, 2019, https://nqcc.wcbailey.net/ ] Rotational spectroscopy relies on quantum chemical calculations to interpret hyperfine splitting.