This project applies the first-principle approach based on density functional theory to investigate the physical and chemical properties of iron and iron alloys for a wide range of pressures and temperatures encompassing conditions for the Earth's inner core. The approach makes no assumptions on the nature of chemical bonding in materials and has been shown to be an ideal complement to experimental efforts in the understanding of properties of Earth and planetary materials. The results of the simulations advance our understanding of the physico-chemical properties of metallic planetary cores in general and the Earth's core in particular.
The project makes important contributions to the understanding of: a) the effect of light elements on the equation of state and the elastic properties of core materials, namely iron-rich (Fe,X) alloys. For the alloying light element the investigators consider primarily silicon, sulfur and oxygen with abundances that are consistent with current geochemical estimates for the Earth's core. b) Geochemistry as well as previous theoretical work shows that it is unlikely that a single light element can account for the density deficit in the Earth's core. Therefore special attention is paid to combinations of alloying light elements in order to explore possible non-linear elastic effects due to the presence of more than one light element. c) Determination of the stable phase of these alloys at inner core conditions. The cubic phases (fcc and bcc) are expected to show drastically different elastic properties as compared to the hexagonal phase (hcp). Thus knowing the stable phase allows the investigators to advance the understanding of the cause of the seismically observed elastic anisotropy in the Earth's inner core. This knowledge illuminates the connection between inner core fabric and elasticity and allows evaluating various growth models for the Earth's inner core, thus contributing to our understanding of planetary evolution.
The research utilizes ideas and techniques from computational material sciences to address challenging problems in Earth's and planetary sciences. This allows the researchers to gain unique insights into the chemistry of metallic portions of planetary interiors and to formulate a sound mineral physics based model of the most remote central portions of the Earth's and planetary interiors: their metallic cores.
