Speaker
Description
Buried more than 5,000 km beneath the surface, Earth’s inner core remains one of the planet’s most mysterious and inaccessible regions. Seismic data constrain its density and pressure and indicate that it is a solid composed primarily of iron. Yet its temperature, crystal structure, and the origin of the unusually slow seismic-wave propagation remain uncertain. Reproducing inner-core conditions in the laboratory is still extremely challenging. First-principles atomistic simulations based on density-functional theory have provided valuable insights, but their scope has traditionally been limited to small simulation cells. By combining these methods with deep-learning techniques, we extended simulations from a few hundred to more than one million atoms while preserving chemical accuracy in the interatomic interactions. Our simulations indicate that Earth’s inner core is best described as a cubic iron–silicon alloy. This Fe-based solid solution matches seismic observations better than any previously proposed structure and opens new perspectives on the nature of Earth’s deepest interior.