title: Superatomic S(2) silver clusters stabilized by a thiolate-phosphine monolayer: insight into electronic and optical properties of Ag14(SC6H3F2)12(PPh3)8 and Ag16(SC6H3F2)14(DPPE)4.
abstract: The electronic structure of two recently crystallographically solved, thiolate-phosphine protected silver clusters Ag14 and Ag16 are analyzed via density functional theory (DFT) and their optical excitations are analyzed from time-dependent DFT perturbation theory. Both clusters can be characterized as having the S(2) free-electron configuration in the metal core, which is the first time such a configuration is confirmed for structurally known ligand-protected noble metal clusters. However, their different core shapes and ligand layer induce significantly different optical spectra. Performance of gradient-corrected DFT functionals is discussed and it is shown that the asymptotically correct Leeuwen-Baerends LB94 functional reproduces the optical spectrum of Ag14 in a good agreement with experiment. Choice of the functional becomes important for clusters where the optical transitions are dominated by the electron-rich ligand layer.
authors.affiliation: Department of Chemistry, Nanoscience Center, University of Jyväskylä , FI-40014 Jyväskylä, Finland.
authors.forename: Lars
authors.initials: L
authors.lastname: Gell
authors.forename: Lauri
authors.initials: L
authors.lastname: Lehtovaara
authors.forename: Hannu
authors.initials: H
authors.lastname: Häkkinen