Ab initio calculations of the elasticity of iron and iron alloys at inner core conditions: Evidence for a partially molten inner core?

Ab initio finite temperature molecular dynamics simulations have been used to calculate the elasticity of hcp-Fe, bcc-Fe, FeS and FeSi at core conditions. The calculated compressional wave velocities are in excellent agreement with the most recent experimental data. However, the calculated shear wave velocities of all phases studied are significantly higher than those inferred from seismology. This discrepancy can only be explained if the inner core is partially molten containing more than ∼ 8% liquid.