The vibrational properties of benzene on an ordered water ice surface

Clark, Victoria H.J.; Benoit, David M.

Abstract

We present a hybrid CCSD(T) + PBE-D3 approach to calculating the vibrational signatures for gas-phase benzene and benzene adsorbed on an ordered water ice surface. We compare the results of our method against experimentally recorded spectra and calculations performed using PBE-D3-only approaches (harmonic and anharmonic). Calculations use a proton ordered XIh water ice surface consisting of 288 water molecules, and results are compared against experimental spectra recorded for an ASW ice surface. We show the importance of including a water ice surface into spectroscopic calculations, owing to the resulting differences in vibrational modes, frequencies, and intensities of transitions seen in the IR spectrum. The overall intensity pattern shifts from a dominating ν11 band in the gas-phase to several high-intensity carriers for an IR spectrum of adsorbed benzene. When used for adsorbed benzene, the hybrid approach presented here achieves an RMSD for IR active modes of 21 cm-1, compared to 72 cm-1 and 49 cm-1 for the anharmonic and harmonic PBE-D3 approaches, respectively. Our hybrid model for gaseous benzene also achieves the best results when compared to experiment, with an RMSD for IR active modes of 24 cm-1, compared to 55 cm-1 and 31 cm-1 for the anharmonic and harmonic PBE-D3 approaches, respectively. To facilitate assignment, we generate and provide a correspondence graph between the normal modes of the gaseous and adsorbed benzene molecules. Finally, we calculate the frequency shifts, Δν, of adsorbed benzene relative to its gas-phase to highlight the effects of surface interactions on vibrational bands and evaluate the suitability of our chosen dispersion-corrected density functional theory.

Citation

Clark, V. H., & Benoit, D. M. (2021). The vibrational properties of benzene on an ordered water ice surface. Monthly notices of the Royal Astronomical Society, 508(3), 3239-3250. https://doi.org/10.1093/mnras/stab2670

• Journal Article Type: Article
• Acceptance Date: Sep 10, 2021
• Online Publication Date: Sep 20, 2021
• Publication Date: 2021-12
• Deposit Date: May 19, 2022
• Publicly Available Date: May 27, 2022
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 508
• Issue: 3
• Pages: 3239-3250
• DOI: https://doi.org/10.1093/mnras/stab2670
• Keywords: Astrochemistry; Molecular data; Dust; Extinction; ISM: molecules; Infrared: ISM
• Public URL: https://hull-repository.worktribe.com/output/3809330