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RESEARCH PRODUCT

Effects of Silver Doping on the Geometric and Electronic Structure and Optical Absorption Spectra of the Au_{25-n}Ag_{n}(SH)_{18}^{-} (n = 1, 2, 4, 6, 8, 10, 12) Bimetallic Nanoclusters

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The effect of silver doping of the Au25(SH)18– nanoparticle is studied by investigating Au25–nAgn(SH)18– (n = 1, 2, 4, 6, 8, 10, 12) systems using DFT. For n = 1, doping of the icosahedral shell of the metal core is energetically more favorable than doping of the metal–thiolate units or the center of the core. For n ≥ 2, only doping of the core surface is considered, and arrangements where the silver dopants are in close proximity tend to be slightly less favorable. However, energy differences are small, and all conformations are accessible under experimental conditions. Boltzmann-averaged excitation spectra for these systems show similar features to the undoped Au25(SH)18–. The main differences include a blue shift of the low-energy HOMO–LUMO (1P→1D) peak and an increased intensity of the peak at 2.5 eV as the number of doping silver atoms increases. Silver doping lowers the energy of ligand-based orbitals and facilitates the transitions between the superatom orbitals. Silver-doped systems show broader e...