Fig. 4: Comparative projected electronic density of states (PDOS) of the clusters.

a–d The HOMO-LUMO energy gap of each cluster is centered around zero and the magnitude of the gap is presented. The Au-incorporated clusters, AuAg16 and AuAg12Cu4, manifest the most substantial HOMO-LUMO gaps, measuring 2.25 and 2.28 eV respectively whereas the Ag17 and Ag13Cu4 clusters display band gaps of 2.09 eV.