Influence from connection of atomic clusters on the second peak splitting of pair distribution function in metallic glasses

In this study, molecular dynamics simulations were carried out to interpret the splitting of the second peak in the pair distribution function (PDF) of Cu monatomic metallic glass (MG). The atomic packing in Cu MG can be described globally as a superposition of the spherical-periodic order and the local translational symmetry. Voronoi tessellation analyses indicate that the dominant cluster is the crystal-like polyhedron <0, 3, 6, 4>. Furthermore, the diversity of connection of atomic clusters results in the splitting of the second peak. The first sub-peak originates from the face-sharing clusters and the second one results from the alignment of the central atoms and the sharing atom of two vertex-sharing clusters. Moreover, the result shows that the right sub-peak of the splitting second peak is due to the icosahedral- and crystal-like polyhedra, whereas the left sub-peak is essentially due to the crystal-like clusters.