Graduate student Thomas Ellington will present “Computational Investigation into the Hydration of Sulfuric Acid: H2SO4(H2O)n where n = 1-5″ a seminar to the department.
This study examines hydrated sulfuric acid clusters, H2SO4(H2O)n where n = 1-5. The structures, energetics, and thermodynamic properties of these clusters are computed. For each isomer, canonical second-order Møller-Plesset perturbation theory (MP2) was utilized along with a series of Dunning’s correlation consistent basis sets augmented with diffuse functions on all non-hydrogen atoms (heavy-aug-cc-pVXZ, where X = D, T, and Q) to determine structures and corresponding harmonic vibrational frequencies. Discrepancies in previous literature lead to uncertainties when predicting the most thermodynamically favourable hydrates1-3. To resolve this ambiguity, free energies of binding are computed to determine sequential cluster growth for nucleation. Atmospheric aerosols are known to have a significant net cooling effect on the atmosphere. Of all atmospheric aerosols, sulfates contribute most to the global radiation balance and have the ability to serve as important cloud condensation nuclei (CCN) due to their tendency to form large hydrated clusters. CCN’s, when in high concentrations, can increase cloud reflectivity and consequently will reduce the amount of solar radiation reaching the Earth’s surface.
- A.Bandy and J. Ianni. Study of the Hydrates of H2SO4 Using Density Functional Theory . J. Phys. Chem. A 1998, 102, 6533-6539.
- Theo Kurtén et al. Quantum chemical studies of hydrate formation of H2SO4 and HSO4–. Boreal Environment Research, 12:431-453, 2007.
- George C. Shields et al. Quantum Mechanical Study of Sulfuric Acid Hydration: Atmospheric Implications. J. Phys. Chem. A 2012, 116, 2209-2224.