Understanding Crystallization from First Principles

CIC nanoGUNE Seminars

Pablo Piaggi
CIC nanoGUNE Seminar room, Tolosa Hiribidea 76, Donostia-San Sebastian
Emilio Artacho
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Understanding Crystallization from First Principles

Crystallization is a process of key importance for many modern technologies, including climate change mitigation via carbon mineralization and the manufacturing of pharmaceuticals, and it also plays a central role in geological, planetary, and climate sciences. In spite of its importance, the microscopic crystallization mechanisms of many systems are still today unknown due to the short time and length scales involved in the process. Molecular dynamics simulations are an attractive tool to provide atomistic insight into the complex, and often elusive, crystallization mechanisms. However, a severe limitation of such simulations is their reliance on simple semiempirical models for the interatomic interactions. These models often fail to describe accurately the properties of the system under study, or cannot capture important physical processes, such as the cleavage and formation of chemical bonds. An alternative to this approach are first principles, or ab initio, molecular dynamics simulations based on forces calculated on-the-fly from ground-state quantum-mechanical electronic-structure calculations. Although highly accurate, ab initio molecular dynamics come at a great computational cost, an issue that hampered their application to study crystallization for several decades. Recent advances in artificial intelligence have allowed for the construction of ab-initio machine-learning interatomic potentials, a ground-breaking simulation tool which decreases the cost of ab initio molecular dynamics by more than three orders of magnitude and also provides access to systems with millions of atoms. In this talk, I will provide an overview of this simulation methodology, and show a variety of applications, including crystallization from the bulk, at interfaces, and in solution. In particular I will present results for the calculation of homogeneous ice nucleation rates from first principles [1], and some insights into the formation of ice at the surface of the mineral feldspar, the most important ice nucleating particle in our planet's atmosphere [2]. I will end by discussing some of the activities I intend to carry out at CIC nanoGUNE in the context of the Ikerbasque Research Fellowship.

[1] Piaggi, Weis, Panagiotopoulos, Debenedetti, and Car, Proc. Natl. Acad. Sci. 119, 33 (2022)

[2] Piaggi, Selloni, Panagiotopoulos, Car, and Debenedetti, Faraday Discuss. 249, 98 (2023)