First-principles predictions of transport properties of liquid and solid Fe-Si alloys at Earth core conditions

Transport properties such as thermal and electrical conductivities of the liquid iron-rich alloy are critical in understanding the history of Earth's core, the evolution of the geomagnetic field, and the heat budget of the Earth. Recent measurements on Fe-Si alloy [1] reported very low thermal conductivity at ambient temperature up to 120 GPa. First-principles simulation allows explorations of a wider range of conditions and reconcile with the experimental findings. Kubo theory is used to compute transport properties from first-principles molecular dynamics (FPMD)simulations, incorporating scattering of electrons by disorder and thermal vibrations usingdensity functional theory, and by other electrons via dynamical mean field theory which isimplemented in the SPRKKR code. Studying both solid and liquid FeSi, we measure the anisotropy, address the saturation effects, and calibrate the violation of the Wiedemann-Franz law. The implication of these findings to the heat budget will be discussed.

This work is supported by U.S. NSF CSEDI grant EAR-1901813 and the Carnegie Institution for Science. We gratefully acknowledges the Gauss Centre for Supercomputing e.V. (www.gauss-centre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC at Leibniz Supercomputing Centre (LRZ, www.lrz.de).J.M. thank the CEDAMNF Project financed by the Ministry of Education, Youth and Sports of Czech Republic, Project No. CZ.02.1.01/0.0/0.0/15_003/0000358 and the Czech Science Foundation (GACR), Project No. 20-18725S.