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

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 differ…