Sextic centrifugal distortion constants: interplay of density functional and basis set for accurate yet feasible computations

Abstract

Quantum-chemical calculations assist the analysis of laboratory spectra, and often provide the only means to determine spectroscopic data that cannot be accessed experimentally. Accurate predictions of vibrational and rotational spectroscopic parameters are required for applications in the field of high-resolution molecular spectroscopy. While the accuracy issue of the quantum-chemical calculation of vibrational properties and of equilibrium structures has been addressed in the literature, the same is not true for centrifugal distortion constants that however play an essential role for the interpretation of remote sensing data. In this work, the performance of several model chemistries, rooted mainly in density functional theory, in computing sextic centrifugal distortion constants is assessed employing a benchmark set of molecules of both atmospheric and astrochemical relevance. The Jensen’s (aug-)pcs-n basis sets, different flavours of Dunning’s triple-ζ basis sets and the SNSD basis set, are employed in conjunction with different functionals, and their predictions are benchmarked against experimental and theoretical data at the coupled cluster level of theory. This study also demonstrates the reliability of the calculation of sextic centrifugal distortion constants within the Gaussian16 rev. B.01 program package. Reliable predictions of the sextic centrifugal distortion constants for the gauche- and trans-conformers of ethyl-mercaptan are also presented.

GRAPHICAL ABSTRACT

KEYWORDS:

• Quantum-chemical calculations
• rotational spectroscopy
• infrared spectroscopy
• high-resolution spectroscopy
• benchmark

Acknowledgements

Prof. C. Puzzarini is acknowledged for providing theoretical harmonic frequencies of vibration of CH₃F and oxirane and Dr. Giorgia Ceselin is acknowledged for useful comments. The SMART@SNS Laboratory (http://smart.sns.it) is acknowledged for providing high-performance computer facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Italian Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) under Grants 2015F59J3R (PRIN 2015, project ‘Simulation Tools for Astrochemical Reactivity and Spectroscopy in the Cyberinfrastructure’, STARS in the CAOS) and 2017A4XRCA (PRIN 2017, project ‘Physico-chemical Heuristic Approaches: Nanoscale Theory Of Molecular Specroscopy’, PHANTOMS); by Scuola Normale Superiore under Grants GR16_B_TASINATO and SNS18_B_TASINATO; and by Università Ca’ Foscari – Venezia under Grant Adir funds.