In classical electrodynamics, a plasmon is defined as a collective and coherent oscillation of the delocalized conduction electrons of the noble metal nanostructure in response to an applied electromagnetic field. A way of translating this definition in the quantum mechanical framework consists in identifying electronic excitations (i ) involving conduction band electrons, and displaying a (ii ) collective and (iii ) coherent character. On this line, Gieseking and coworkers recently developed a series of 3 analytical indexes to systematically identify plasmon-like excitations computed at TDDFT level in noble metal nanoclusters. With the aim of quantifying the plasmon-like excitations in the noble metal nanoclusters investigated here, we adapted the implementation of the first two of these indexes to the sTDA framework, i.e., the superatomic character and collectivity indexes. Their implementation is available in Ref. 87. Since we presently don't have easily access to the transition dipole moment, we left the dipole additivity index.