Unraveling the Tropospheric Microhydration Processes of Iodous Acid HOIO

The microhydration of iodous acid has been theoretically studied using the coB97X-D/aug-cc-pVTZ level of theory. Two hydration processes have been examined considering the addition of either successive water molecules or water clusters with a number of water molecules from 1 to 4. The singlet potential energy surface exploration revealed four monohydrates, seven dihydrates, nine trihydrates, and ten tetrahydrates. The thermodynamic properties of the hydration reactions have been calculated at different levels of theory including density functional theory and coupled cluster calculations DK-CCSD(T) with the ANO-RCC-VQZP basis sets. Standard reaction enthalpy and standard Gibbs free reaction energy were Computed. The temperature dependence of Delta(r)G degrees (T) was evaluated for all studied aggregates over the temperature range of 200-400 K. The results showed that the hydrated forms of HOIO can exist in tropospheric conditions. Atmospheric implications in terms of assessing the molecular concentrations of HOIO and water aggregates are discussed.