Ab initio molecular dynamics study of Se(iv) species in aqueous environment

Abstract

An ab initio molecular dynamics investigation is carried out on various water-borne Se(IV) species, H₂SeO₃, HSeO₃⁻ and SeO₃²⁻, in aqueous environment. Consistent with the reported acid dissociation constants, in neutral solution H₂SeO₃ exchanges protons with the surrounding water molecules establishing a dynamic equilibrium with HSeO₃⁻. The SeO₃²⁻ species is found to be stable only in basic environment, which is emulated in the present simulation through introducing a hydroxide ion, OH⁻, in the system. The hydration structure, hydrogen bonding and spectroscopic signatures of the species are comprehensively analyzed. The influence of the solute's hydration structure on the structural and dynamic response of the solvent is discussed. The correlation between the strength as well as the number of hydrogen bonds accepted by the solute on its vibrational properties are analyzed.