Amorphicity and structural changes in binary clusters

Based on the structural and energetic properties of an atomistic cluster a method to measure the degree of amorphousness of the cluster is proposed. The proposed method is applied to gold-copper nanoalloys with sizes of 38, 55, 365, 933 atoms, and with structural and energetic properties obtained through molecular dynamics simulation and the Gupta potential model. Results show that structures with a low degree of amorphousness have perfect or distorted geometries which are fully identified as Mackay icosahedron, truncated octahedron, pancake, or fcc, while those with a high degree of amorphousness are also fully identified as amorphous, in agreement with results reported in the literature. The proposed method should be a promising tool to easily identify how ordered or disordered an atomistic cluster is, as well as for the easily identification of the local environment of the core or surface atoms of the cluster, among others. Graphical abstract