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The structure of liquid and rapid quenched amorphous Ag 0.74 Ge 0.26 alloy at the eutectic composition was studied by ab initio molecular dynamics (MD) simulations. The local structural properties from the liquid at 1123 K to amorphous solid at 300 K were systematically investigated. The pair-correlation function at 1123 K from the MD simulations agrees well with the experimental data. The local structures were also analyzed using Honeycutt-Andersen (HA) indices, Voronoi tessellation, and atomic cluster alignment (ACA) method. The HA indices analysis reveals that pentagonal bipyramid structure has high population which become more predominant upon solidification. Voronoi tessellation analysis indicates strong icosahedral short-range orders (SRO) in the liquid and amorphous samples generated by the MD simulations. Using the ACA, the development of icosahedral SRO upon cooling is further confirmed and a Bergman medium-range order is also observed. The analysis of structural properties and chemical short-range order suggests that Ag atoms trend to have a Bergman-like packing, while the dispersed Ge atoms prevent the alloy from forming a long-range order upon cooling. The Bergman medium-range order is also confirmed by the constrained Reversed Monte Carlo results.

The structures and dynamics of liquid Ag 74 Ge 26 alloy at different temperatures were investigated by high-energy X-ray diffraction and ab initio molecular dynamics simulation. The calculated structure factors agree remarkably well with the experimental data. Local atomic structure orders have been characterized by angular distribution functions, Honeycutt-Andersen index, Voronoi tessellation and the atomic cluster alignment. We reveal that (i) <0,