title: Role of vibrational anharmonicity in atmospheric radical hydrogen-bonded complexes.
abstract: Harmonic and anharmonic vibrational frequency calculations are reported for the most stable hydrogen bonded complexes formed between the hydroperoxyl radical and formic, acetic, nitric, and sulfuric acids which are of atmospheric interest. A comparison between the calculated IR spectra of the hydrogen bonded complexes with the corresponding separate monomers is also reported with the aim to facilitate a possible experimental identification of these complexes. The calculations have been carried out using the second-order vibrational perturbative treatment implemented by Barone applied to the PES obtained with the B3LYP functional using the 6-31+G(d,p) and 6-311+G(2d,2p) basis sets. Our calculations for the separate monomers predict vibrational frequencies with quite a good agreement with the experimental values. The anharmonic contribution results in differences of around 40 cm(-1) with respect to the harmonic values; although in some cases involving highly anharmonic modes, these differences can rise up to 300 and 450 cm(-1).
authors.affiliation: Eenheid Algemene Chemie (ALGC), Faculteit Wetenschappen Vrije Universiteit Brussel Pleinlaan 2, 1050 Brussels, Belgium. mtorrent@vub.ac.be
authors.forename: M
authors.initials: M
authors.lastname: Torrent-Sucarrat
authors.forename: J M
authors.initials: JM
authors.lastname: Anglada
authors.forename: J M
authors.initials: JM
authors.lastname: Luis
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D001272:Atmosphere; D001671:Biochemistry / Q000379:methods*; D002627:Chemistry, Physical / Q000379:methods*; D005561:Formates / Q000737:chemistry; D005609:Free Radicals; D006860:Hydrogen Bonding; D017665:Hydroxyl Radical; D008968:Molecular Conformation; D017942:Nitric Acid / Q000737:chemistry; D016011:Normal Distribution; D010777:Photochemistry / Q000379:methods; D012984:Software; D013055:Spectrophotometry, Infrared / Q000379:methods; D013464:Sulfuric Acids / Q000737:chemistry
chemical_list: D005561:Formates; D005609:Free Radicals; D013464:Sulfuric Acids; C030544:formic acid; D017665:Hydroxyl Radical; D017942:Nitric Acid; C033158:sulfuric acid; D019342:Acetic Acid