Ionized [formula omitted] and [formula omitted] in aqueous environment: Ab initio QMCF-MD studies

Abstract

Ab initio quantum mechanical charge field molecular dynamics (QMCF-MD) simulations were performed for CO2+ and SO2+ in water at the restricted open-shell Hartree–Fock (ROHF) level of theory employing Dunning DZP basis sets for solute and solvent molecules. Simulation data of these hydrated ionic species were compared to their corresponding neutral precursors, CO2 and SO2 illustrating contrasting structures and dynamical behavior. Hydrated CO2+ is subject to weaker hydration than CO2 whereas SO2+ associates with water molecules via stronger H-bonds than SO2, CO2+ and CO2 molecules. Ionization of both gases also leads to a different relative influence on the hydration behavior in aqueous environment reflected by COwat and SOwat mean distances of ∼3.1Å and ∼2.7Å in hydrated CO2+ and SO2+, respectively. In a cloudy atmosphere hydrated CO2+ and SO2+ can produce other oxidized species, which are thought to be partly implicated in earth’s temperature activity.