Theoretical study on a novel Au _{99+31 <i>n</i>} (SR) _{40+10 <i>n</i>} cluster sequence with <i>D</i> ₅ symmetry

The cluster sequences with analogous structures are of significant importance for elucidating the evolutionary patterns in both structural configurations and electronic architectures of RS-AuNCs. Despite substantial efforts devoted to synthesizing and characterizing a series of single-crystal structures of RS-AuNCs, the scarcity of well-defined single-crystal structures for large-sized cluster sequences has impeded comprehensive understanding of structure-property correlations within this size regime. This work presents a theoretical investigation of a novel series of Au_{99+31<i>n</i>}(SR)_{40+10<i>n</i>} (where <i>n</i> = 0, 1, 2, 3) clusters exhibiting <i>D</i>₅ symmetry. The structural evolution of the cluster sequence emerges as a one-dimensional linear extension of the Au₉₉(SR)₄₀ (<i>n</i> = 0) kernel framework, demonstrating a quantized growth pattern where each successive expansion event is accompanied by a precise 21 valence electron increment. The DFT calculations reveal that this series of clusters exhibit significantly negative average formation energies (<i>E</i>_ave), confirming their exceptional thermodynamic stability. The sTDA calculations demonstrate that Au₁₆₁(SR)₆₀ and Au₁₉₂(SR)₇₀ clusters display characteristic surface plasmon resonance (SPR) peak in their UV-Vis, indicating a size-induced transition from molecular to metallic states in these clusters. Furthermore, the aspect ratio is proposed as a potential critical geometric parameter governing the emergence of metallic characteristics in the Au₁₉₂(SR)₇₀ cluster.