Theoretical exploration of global minima, magnetism, structural stability and growth pattern of holmium-doped silicon HoSin0/- (n=10-18) nanoclusters

The structural growth pattern of medium-sized holmium-doped silicon nanoclusters HoSin0/- (n = 10-18) was systematically probed by means of unbiased structure searches and double-hybrid density functionals. The identified global minima of the nanoclusters have been confirmed by comparing the calculated spectral properties such as photoelectron spectroscopy, adiabatic electron affinities and vertical detachment energies with the experimental data. The structural evolution reveals Ho-linked configuration for neutral and anionic nanoclusters (starting from n = 10 and 12, respectively). In this configuration, the linker Ho atom connects two small silicon sub-clusters. The nanoclusters starting from n = 16 prefer the configuration in which Ho atoms reside in the center of Si-cluster. The natural population analysis interprets the involvement of 4f electron of Ho atom in bonding. The participation in bonding has been traced by a transition of an electron from 4f to 5d orbital. This also results in larger magnetic moments (4 and 5 mu(B)) than that of an isolated Ho atom. The HoSi16- nanocluster has good thermodynamic and moderate chemical stabilities as corroborated by average bond energy analysis, highest occupied molecular orbital-lowest unoccupied molecular orbital gap, and chemical bonding, thus suggesting it the most appropriate building block for new functional nanomaterials.

Automated summary

The structural growth pattern of medium-sized holmium-doped silicon nanoclusters was systematically probed through computational and experimental comparisons. The involvement of holmium atoms led to larger magnetic moments in the nanoclusters, with HoSi16- being suggested as the most suitable building block for new functional nanomaterials.