Thanks to the use of artificial intelligence methods, ICTP (International Center for Theoretical Physics) researchers Zhi Li and Sandro Scandalo have succeeded in investigating the role played by silicon within the Earth’s inner core. Published in the journal Nature Communications, the study, funded under Spoke 7 ‘Materials and Molecular Sciences’ of the ICSC – Italian Research Center on HPC, Big Data and Quantum Computing, benefited from special early access to CINECA’s Leonardo supercomputer for training artificial intelligence models. The results obtained demonstrate how silicon, one of the main light elements that make up the ferrous alloy of which the core is composed, profoundly influences the order in which atoms arrange themselves in the ferrous alloy under extreme pressure and temperature conditions, stabilizing the alloy in a cubic rather than hexagonal structure. This discovery could explain why seismic waves travel very slowly through the inner core.
Located more than 5,000 kilometers beneath the Earth’s surface, where temperatures exceed 6,000 degrees Celsius and pressure is more than three million times the standard atmospheric pressure, the planet’s inner core cannot be observed directly and numerical simulations have been key to access its secrets. Most of the studies done until now have only focused on pure iron, showing that in such extreme conditions it crystallizes into a hexagonal structure.
Observations, however, have revealed that seismic waves propagate through the Earth’s core much more slowly than they would in a hexagonal lattice. Li and Scandolo’s results could finally tell us why. “Many hypotheses have been made so far,” says Scandolo, “Our results predict that the seismic wave velocity in the iron-silicon alloy closely matches observed values, strongly suggesting that the atoms in the inner core form a cubic structure.”
The study is the first to consider the role played by light elements such as silicon—which is about half as heavy as iron—in the inner core, something that has only been made possible by AI. This is because assessing the role played by silicon atoms in the alloy requires considering all the many random arrangements in which they can be found. Such a large number of configurations is simply impossible to simulate with traditional methods. The AI algorithms used by Li and Scandolo, instead, are trained to efficiently compute the forces between each pair of atoms, and can therefore deal with larger and more complex systems, over longer time scales.
Read the full press release: https://www.ictp.it/news/2025/8/ai-sheds-new-light-earths-inner-core
