Efficiency in identification of internal structure in simulated monoatomic clusters: Comparison between common neighbor analysis and coordination polyhedron method

Efficiency of two methods for structural analysis, the Common Neighbor Analysis (CNA) from the program OVITO and the Coordination Polyhedron Method (CPM), was compared when applied to detect all possible structural atoms in monoatomic test clusters. The analyzed clusters are in the form of spherical fragments of a pure or disturbed crystal structure or they represent Mackay icosahedra. It was observed that the number of detected structural atoms for both methods is initially similar but decreases rapidly with the increase of applied random translations of atoms. CNA gives higher number of detected structural atoms representing bulk-centered cubic structure, while CPM has significant advantage in detection of icosahedral units. CNA is unable to identify decahedral units; therefore, this method fails to visualize clearly any global symmetry in internal cluster structure. Attempts are made to understand the reasons for the poor performance of both methods in the mentioned aspects and some ways are proposed to improve them.