Structure identification of endohedral golden cage nanoclusters†
Using the Saunders “Kick” global search technique combined with density-functional theory calculations, we have performed an extensive search to obtain the ground state geometries of both neutral and anionic Au16 cages doped systematically with an external atom of different valence electrons: Y, Zr, and Nb. The structural and electronic properties of the doped clusters, MAu16q (M = Y, Zr and Nb; q = 0, −1) are investigated with the aid of previous photoelectron spectroscopy (PES) and theoretical calculations. It is found that the early 4d transition-metals Y, Zr and Nb can be stably encapsulated in the Au16− cage, forming endohedral structures with lager distortion from the parent Au16− cage. Characteristics of the ZrAu16 cluster include its remarkably high average binding energy, doping energy and HOMO–LUMO gap, which reflects its high stability. Furthermore, natural population analysis indicates that a strong ionic bond interaction is revealed in the present study.