A metric to gauge local distortion in metallic glasses and supercooled liquids

We propose a new structural descriptor to characterize distortion and short-range order in metallic glasses and supercooled liquids. Through the new metric, salient structural differences in local clusters of identical Voronoi indices can be accurately identified. As a test case, we employ the short-range-order symmetry parameter (SSP) in atomistic configurations of CuZr generated through extensive molecular dynamics simulations at various temperatures. Structural analysis reveals the dependence of short-range order on local chemistry and thermal fluctuations. Furthermore, the new descriptor can be directly correlated with the atomic level shear stress, the local potential energy surface and the dynamical heterogeneity. Combined with existing analytical tools, the SSP can provide significant information, at the atomic level, on the structure-property relation in metallic glasses and in general complex particulate systems.