An ab initio variationally computed room-temperature line list for 32S16O3

Abstract

Ab initio potential energy and dipole moment surfaces are computed for sulfur trioxide (SO₃) at the CCSD(T)-F12b level of theory with appropriate triple-zeta basis sets. The analytical representations of these surfaces are used, with a slight correction, to compute pure rotational and rotation–vibration spectra of ³²S¹⁶O₃ using the variational nuclear motion program TROVE. The calculations considered transitions in the region 0–4000 cm⁻¹ with rotational states up to J = 85. The resulting line list of 174 674 257 transitions is appropriate for modelling room temperature ³²S¹⁶O₃ spectra. Good agreement is found with the observed infrared absorption spectra and the calculations are used to place the measured relative intensities on an absolute scale. A list of 10 878 experimental transitions is provided in a form suitable for inclusion in standard atmospheric and planetary spectroscopic databases.