Ion Solvation at Thermodynamic Extremes from First-principles Simulations

The properties of aqueous salt solutions at high pressure and temperature are crucial to understanding geochemically relevant fluids. We report on the properties of aqueous monovalent ions at high pressure and temperature (1 GPa/1000 K, 11 GPa/1000 K), as obtained from first-principles molecular dynamics simulations. In particular, we present the effect of ions on the structure and diffusion of water and the effect of water dissociation occurring under pressure on ion solvation. We further analyze vibrational signatures of solvated ions by comparing computed infrared and Raman spectra of salty and pure water at the same conditions. Finally, we present comparative results for ionic conductivity, dielectric constants and molecular polarizabilities of aqueous ionic solutions under pressure.