Ab initio phase diagram and nucleation of gallium

HY Niu and L Bonati and PM Piaggi and M Parrinello, NATURE COMMUNICATIONS, 11, 2654 (2020).

DOI: 10.1038/s41467-020-16372-9

Elemental gallium possesses several intriguing properties, such as a low melting point, a density anomaly and an electronic structure in which covalent and metallic features coexist. In order to simulate this complex system, we construct an ab initio quality interaction potential by training a neural network on a set of density functional theory calculations performed on configurations generated in multithermal- multibaric simulations. Here we show that the relative equilibrium between liquid gallium, alpha-Ga, beta-Ga, and Ga-II is well described. The resulting phase diagram is in agreement with the experimental findings. The local structure of liquid gallium and its nucleation into alpha-Ga and beta-Ga are studied. We find that the formation of metastable beta-Ga is kinetically favored over the thermodinamically stable alpha-Ga. Finally, we provide insight into the experimental observations of extreme undercooling of liquid Ga.

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