Events

Presentation by Dr. Renata Wentzcovitch.

Simulating Iron at Earth’s Core Conditions: From Atomic Processes to Geophysical Implications

Understanding the structure, dynamics, and evolution of Earth’s core requires predictive modeling of iron and its alloys under extreme pressure and temperature. Recent advances in ab initio and machine-learning–driven simulations have transformed this field, enabling direct computation of phase equilibria, superionic transport, and nucleation processes at conditions beyond experimental reach. This talk will highlight a sequence of recent breakthroughs:

1. Large-scale molecular dynamics (MD) simulations demonstrated a two-step nucleation mechanism, i.e., the bcc-mediated crystallization of hcp iron that alleviates the “inner-core nucleation paradox” and constrains the onset of core solidification
2. High-pressure experiments combined with adaptive genetic algorithms revealed unexpected Fe-rich Fe–O compounds (Fe₂₅O₁₃, Fe₂₈O₁₄) with close-packed layered structures, offering potential explanations for seismic and compositional heterogeneity in the inner core
3. Using deep-learning interatomic potentials with explicit electronic-entropy terms, we accurately reproduced themelting temperature of Fe at inner-outer-core conditions (~6,200 K), reconciling discrepancies among experiments and previous simulations and establishing a foundation for data-driven multicomponent models
4. Using hybrid ab initio MD and Monte Carlo sampling, we constructed the Fe–Ni phase diagram at 323 GPa, showing that nickel strongly stabilizes body-centered cubic (bcc) structures and enables bcc–hcp coexistence, suggesting a multilayered inner-core architecture
5. Extending this approach to Fe–O alloys, we developed the first ab initio superionic–liquid phase diagram of Fe₁₋ₓOₓ, revealing that oxygen forms superionic states in both hcp and bcc Fe, enhances cooperative Fe diffusion, and alters light-element partitioning between the inner and outer cores

Together, these results depict the inner core as a compositionally stratified system where metastable, superionic, and composite phases coexist.