Silica under high pressure: How coesite transforms into new exotic phases

What is it about?

This work shows how silica, one of the most abundant minerals in the Earth’s crust behaves under extreme pressures using advanced computer simulations, such as metadynamics combined with a modern machine-learning potential. We focused on coesite, a complex crystalline form of silica, and explored how it transforms into denser phases when compressed far beyond its usual stability range. We captured all experimentally observed transformation pathways - from disordered structures to defective octahedral phases to exotic dense crystals known as coesite-IV and coesite-V.

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Photo by Marjolijn van Raaij on Unsplash

Photo by Marjolijn van Raaij on Unsplash

Why is it important?

Understanding these pathways helps explain how silica behaves deep inside Earth, where extreme pressures shape geological processes. Our results also show that advanced computer simulations can reproduce complex experimental findings and uncover atom-by-atom mechanisms that are otherwise hidden. The unique achievement of this work is capturing all experimentally observed outcomes within a single computational framework, strengthening the link between simulation and experiment and advancing methods to study materials under extreme conditions. In particular, our approach finds the coesite-IV and -V, previously believed to be very difficult to find by standard computational approaches.

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