We report on the thermal and electrical conductivities of two liquid silicon-oxygen-iron mixtures (Fe${}_{0.82}$Si${}_{0.10}$O${}_{0.08}$ and Fe${}_{0.79}$Si${}_{0.08}$O${}_{0.13}$), representative of the composition of the Earth's outer core at the relevant pressure-temperature conditions, obtained from density functional theory calculations with the Kubo-Greenwood formulation. We find thermal conductivities $k=100\left(160\right)$ W m${}^{-1}$ K${}^{-1}$, and electrical conductivities $\sigma =1.1\left(1.3\right)\times {10}^6{\Omega }^{-1}$ m${}^{-1}$ at the top (bottom) of the outer core. These values are between two and three times higher than previous estimates, and have important implications for our understanding of the Earth's thermal history and the functioning of the Earth's magnetic field, including rapid cooling rate for the whole core or high level of radiogenic elements in the core. We also show results for a number of structural and dynamic properties of the mixtures, including the partial radial distribution functions, mean square displacements, viscosities, and speeds of sound.

• Received 12 November 2012

DOI:https://doi.org/10.1103/PhysRevB.87.014110