Ab initio free energy calculations of the solubility of silica in metallic hydrogen and application to giant planet cores

By combining density functional molecular dynamics simulations with a thermodynamic integration technique, we determine the free energy of metallic hydrogen and silica, SiO2, at megabar pressure and thousands of degrees Kelvin. Our ab initio solubility calculations show that silica dissolves into fluid hydrogen above 5000 K for pressures from 10 and 40 megabars, which has implication for the evolution of rocky cores in giant gas planets like Jupiter, Saturn and a substantial fraction of known extrasolar planets. Our findings underline the necessity for considering the erosion and redistribution of core materials in giant planet evolution models but also demonstrate that hot, metallic hydrogen is good solvent at megabar pressures, which has implications for high pressure experiments. Subject headings: planets and satellites: dynamical evolution and stability – planets and satellites: individual (Jupiter, Saturn) – planets and satellites: interiors