Revisiting the cobalt(II) hydration from molecular dynamics and X-ray absorption spectroscopy

Abstract

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 EXAFS and XANES spectra of a dilute Co(II) aqueous solution 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)–H${}_2$O interaction using the hydrated ion model that uses a polarisable 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.

GRAPHICAL ABSTRACT

Keywords:

• Intermolecular potential
• polarisable and flexible model
• MCDHO2 potential
• MD simulation
• power spectrum

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

DZC thanks to Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía of a postdoctoral fellowship (proyecto de excelencia P11-FQM7607). We thank the synchrotron radiation source of SOLEIL (France) for supplying us beamtime at MARS beamline (experimental number 20160305) and Dr. P.L. Solari for the technical support during XAS measurements. We thank the Spanish Ministerio de Ciencia, Innovación y Universidades for financial support (PGC2018-099366-B-I00).