Bork, Nicolai Christian3; Du, Lin3; Kjærgaard, Henrik Grum4
1 Administration, Department of Chemistry, Faculty of Science, Københavns Universitet2 Department of Chemistry, Faculty of Science, Københavns Universitet3 Department of Chemistry, Faculty of Science, Københavns Universitet4 Administration, Department of Chemistry, Faculty of Science, Københavns Universitet
Models of atmospheric aerosol formation are dependent on accurate Gibbs free binding energies (ΔG°) of gaseous acids and bases, but for most acid–base pairs, only ab initio data are available. We report a combined experimental and theoretical study of the gaseous molecular complex of dimethylsulfide (DMS) and HCl. On the basis of infrared spectroscopy and anharmonic local mode calculations, we determine ΔG(295K)° to be between 6.2 and 11.1 kJ mol(–1). We test the performance of MP2 and five often used DFT functionals with respect to this result. M06-2X performs the best, but also the MP2 prediction is within the experimental range. We find that coupled cluster corrections to the electronic energy improves ΔG° estimates if and only if triple excitations are included. These estimates may be further improved by applying vibrational scaling factors to account for anharmonicity. Hereby, all but the PW91 based predictions are within the experimental range.
Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical, 2014, Vol 118, Issue 8, p. 1384-1389