Incorporating Layer Curvature into Atomistic Models of Vernadite Using Molecular Dynamics Simulations

초록

Vernadite, a ubiquitous layered manganese oxide, exerts strong control on metal geochemical cycles in diverse environments. Its nanocrystalline nature imparts high reactivity toward metal adsorption but poses challenges for detailed structural characterization, particularly of the layer curvature. Here, we present the first atomistic models of vernadite with particle dimensions comparable to those observed experimentally, obtained using molecular dynamics (MD) simulations. Analysis of mean and Gaussian curvature computed from the MD trajectories shows that vernadite monolayers adopt anticlastic curvatures, with the degree of curvature modulated by the nature of charge-compensating cations and the spatial distribution of Mn vacancies. We further find that a minimum Mn vacancy concentration of 5% is required for layered structural stability, indicating the essential role of vacancies in maintaining layer integrity. These atomistic structural models of vernadite provide new insights into the structural controls of vernadite's chemical reactivity, advancing our understanding of Mn oxide behavior with broad implications.

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