First-Principle Molecular Dynamics Investigation of Waterborne As-V Species

The toxicity, mobility, and geochemical behaviors of arsenic are known to vary enormously with its speciation and oxidation states. The present work details results on the basis of ab initio molecular dynamics analysis of various waterborne As-V species, namely, H3AsO4, H2AsO4-, HAsO42-, and AsO43-. The nature of hydrogen bonding of these species with water and its influence on the solvent structure and relaxation behavior are discussed. Useful microscopic insights on the structural and spectroscopic signatures of the species in aqueous media are reported. Comparison of normal-mode frequencies of the species in gas phases to the vibrational density of states in solution provides insights on the influences of solvation and H bonding. The results are compared with the previous experimental and simulation studies, where available.