![]() ![]() Previous FPMD simulations were used to provide constraints on possible light-element candidates for the Earth’s outer core considering Si, O, S, and C elements 6. Recent FPMD simulation of liquid Fe–Ni–C at temperatures of ~1673 K and pressure ranging between 0 and 67 GPa demonstrated that the short-range liquid structure in FPMD simulation agrees well with the experiments at similar P– T conditions providing an essential benchmark for simulation 63, 64. Thus, the first-principles molecular dynamics (FPMD) simulations can provide valuable insight into the density and elastic properties of metallic liquids at extreme P–T conditions relevant to Earth’s core 57, 58, 59, 60, 61, 62. However, the validity of Birch’s law for solid iron at very high P– T is debated 56. Since most of the experiments are performed at lower P–T conditions, an empirically established linear relationship between density and sound wave velocity, also known as Birch’s law 54, is usually utilized to extrapolate density and elastic properties at core conditions 55. ![]() To understand the behavior of carbon during large-scale melting during accretion and constrain its abundance in the mantle and core, the partition coefficient of carbon between Fe-rich alloy melt and silicate melt, \(\) even at core–mantle boundary conditions, i.e., 136 GPa 52, 53. Experiments that show such a high concentration of carbon in the Fe-rich melt are generally carbon saturated, whereas the carbon abundance in natural systems is expected to be well below the saturation limit imposed by graphite/diamond. Carbon is highly soluble in metallic Fe-rich melt, with solubility reaching ≥5–8 wt.% at the core and core-forming magma ocean conditions 8, 11, 12. Carbon is one of the important potential light-element candidates in the Earth’s core because of its chemical affinity to the metallic phase and its cosmochemical abundance 4, 8, 9, 10. However, the identity and proportion of the light elements are largely unknown 4, 5, 6, 7. Earth’s core is chiefly iron (Fe) but must contain some proportion of lighter elements to have the density based on the seismological observation 1, 2, 3. ![]()
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