A theoretical study of the structures and optical spectra of helical copper–silver clusters

Christopher J. Heard, Roy L. Johnston

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The structures and optical response of helical clusters (“Bernal spirals”) with compositions Ag12Cu1+ and Ag1Cu12+ are calculated within Kohn–Sham density functional theory and the configuration interaction singles variant of time dependent density functional theory. The effects of dopant position within the cluster on the vertical excitation spectrum are investigated according to the underlying electronic structure of the major transitions. The roles of symmetry and geometry are investigated by calculating the optical response of helical, icosahedral and nanorod-like clusters of Ag13+, finding local structure to be significant in driving the resultant optical response at the subnanometre scale. Further, it is noted that helical clusters have optical properties which are quite distinct from those of nanorods of similar dimensions. The effect of multiple doping is studied by introducing copper atoms into the centre of the silver helix, over the composition range Ag13+ to Ag6Cu7+. There is a complex variation of the major plasmon-like peak over this range, attributed to subtle variations in the influence of the copper 3d band on the excitations and charge transfer for different sites within the cluster. This work suggests that coinage metal nanohelices have unusual, tunable electronic properties, which in addition to their inherent chirality makes them interesting systems to study for chiral catalysis and optoelectronics.
Original languageEnglish
Pages (from-to)21039-21048
Number of pages10
JournalPhysical Chemistry Chemical Physics
Issue number39
Early online date3 Mar 2014
Publication statusPublished - 21 Oct 2014


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