Water Partitioning between Liquid Iron and Silicate Melt at High Pressure and High Temperature (NERC Grant NE/M015181/1, NE/S01134X/1)

The partitioning coefficients of water between iron and silicate melts at 20, 50, 90 and 135 gigapascals (corresponding to 2800, 3500, 3900 and 4200 kelvin) were calculated by using ab initio molecular dynamics and thermodynamic integration techniques. The Gibbs free energy of a series of iron and silicate melts with different concentrations of H2/H2O were calculated. Then the chemical potentials of H2/H2O were derived from the concentration dependent Gibbs free energies at each pressure temperature. The partitioning coefficients can be calculated by equating the chemical potential of H2/H2O in iron and silicate melts. The Weeks-Chandler-Andersen (WCA) system with established thermodynamics was used as the reference.