Probing the structural and electronic properties of lanthanide-metal-doped silicon clusters: M@Si6 (MÂ =Â Pr, Gd, Ho)

► We examine the electronic and structural properties of M@Si6 (M = Pr, Gd, Ho). ► The impurity M in M@Si6− sits on top of the regular pentagonal bipyramid. ► The impurity M in M@Si6 becomes a part of the pentagonal ring. ► The photoelectron spectra are simulated to compare with the experimental results. ► NICS values at various points are calculated to discuss aromaticity.