The stability of small helical gold nanorods: A relativistic density functional study

Multistrand 7‐1 helical Au24, Au32, and Au40 structures with three, four, and five gold atoms in the central strand and 21, 28, and 35 gold atoms in the coaxial tube are investigated using relativistic density functional theory. We demonstrate that these helical gold nanorods are stable structures with a rather large HOMO–LUMO gap, a large binding energy per atom, a very large vertical dissociation energy, and an extremely large electron affinity. On the basis of the atomic charges and the nature of the frontier orbitals, they are also expected to have strong selective reactivity toward electrophiles and nucleophiles. Furthermore, we show that these helical Aun structures and, in particular, the helical Au40 structure are competitive energetically and chemically with respect to alternate cage and compact Aun structures. We consider two fragmentations of the helical Au40 structure and perform a density of states analysis to examine both charge transfer and electronic polarization. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2012