Solvation of halogen ions in aqueous solutions at 500 K–600 K under 100 atm

Structural properties of the pure water and halogen solutions at high temperatures and pressures are studied by using the molecular dynamics simulations and quantum molecular simulations. The related characters are calculated as functions of temperature and pressure. The results show that the hydrogen bonded networks become looser as temperature increases, with the collapse of the traditional tetrahedral structure. It is similar to the concentration-dependent collapse in the NaCl solutions. However, adding other halogen elements has no further effects on the already weakly bonded water molecules. At the phase changing points, the process of hydration is evident for the bigger ions, so that the bigger the ion is, the smaller a cluster is formed. (paper)