Oxidation and Reflectivity of Liquid Gallium Surfaces from Machine-Learning Simulations

Liquid gallium exhibits pronounced layering at its free surface, but its strong tendency to oxidize makes the microscopic picture more complex. While the clean liquid has been widely studied, the structural and morphological changes induced by oxidation remain less explored. Here we perform molecular dynamics simulations with machine-learning interatomic potentials to analyze the surface of liquid gallium in both pristine and oxidized conditions. We compute the X-ray reflectivity and show how the formation and structuring of the oxide layer modify the interfacial morphology and its experimental signature. Our results highlight the key role of oxidation in determining the surface properties of liquid gallium and provide new insights into the connection between atomic-scale morphology and reflectivity.