Structural growth pattern and spectroscopic properties of samarium-doped germanium SmGe_n (n = 6-20) nanoclusters:...

The doping of rare earth elements, renowned as "industrial vitamins", represents a highly viable strategy for developing advanced materials with enhanced performance. Nevertheless, a comprehensive understanding of the specific effects induced by such doped nanoclusters remains elusive, particularly concerning the structural growth patterns following rare-earth doping and their underlying performance-governing mechanisms. To address this knowledge gap, we systematically investigated the structural and electronic properties of samarium-doped germanium clusters using ABCluster global search combined with the double-hybrid mPW2PLYP density functional theory. The results revealed two distinct growth behaviors in the global minimum structures: (1) substitutional structures, where a Sm atom replaces one Ge atom in the ground state structures of anionic Ge_n+1^- (and/or neutral Ge_n+1) clusters; and (2) linked structures, where a Sm connects two germanium subclusters. The system exhibits a clear preference for linked structural motifs with increasing cluster size. We systematically calculated spectral properties including ionization spectra, infrared spectra, Raman spectra, and ultraviolet-visible spectra. These spectral signatures provide complementary approaches for identifying cluster growth behaviors. Furthermore, we analyzed HOMO-LUMO energy gap, relative stability, magnetic properties, and charge transfer characteristics. The results suggest that the superior thermodynamic and chemical stability of SmGe₁₅ and SmGe₂₀ clusters position them as promising candidates for engineering next-generation functional nanomaterials featuring adjustable one- and three-dimensional structural configurations.