Revisiting the Cobalt(II) hydration from Molecular Dynamics and X-ray Absorption Spectroscopy

Solution chemistry of Co(II) is receiving a renewal attention due to the high interest for knowing the speciation in seawater of its 60 Co radioactive isotope which appeared in the Japan sea as a consequence of the Fukushima-Daichii nuclear power plant accident. Experimental EX-AFS and XANES spectra of a dilute Co(II) aqueous solutions have been recorded and structural data derived from their analysis. Based on QM calculations, an ab-initio intermolecular potential has been generated for the Co(II)-H2O interaction using the hydrated ion model that uses a polarizable and flexible solvent description through the MCDHO2 model. Classical molecular dynamics simulations of Co(II) in water have been performed and X-ray Absorption spectra have been simulated and compared with the experimental ones. Energetic, structural, dynamical and spectroscopical properties of the cobalt cation in solution have been computed and compared with previous experimental and theoretical data. These comparisons have assessed the good performance of the developed intermolecular potential. KEYWORDS Intermolecular potential and Polarizable and Flexible model and MCDHO2 potential and MD simulation and power spectrum