Trends in structural, electronic and energetic properties of bimetallic vanadium–gold clusters AunV with n = 1–14

Abstract

A systematic quantum chemical investigation on the electronic, geometric and energetic properties of Au_nV clusters with n = 1–14 in both neutral and anionic states is performed using BP86/cc-pVTZ-PP calculations. Most clusters having an even number of electrons prefer a high spin state. For odd-electron systems, a quartet state is consistently favoured as the ground state up to Au₈V. The larger sized Au₁₀V, Au₁₂V and Au₁₄V prefer a doublet state. The clusters prefer 2D geometries up to Au₈V involving a weak charge transfer. The larger systems bear 3D conformations with a more effective electron transfer from Au to V. The lowest-energy structure of a size Au_nV is built upon the most stable form of Au_n−1V. During the growth, V is endohedrally doped in order to maximize its coordination numbers and augment the charge transfer. Energetic properties, including the binding energies, embedding energies and second-order energy differences, show that the presence of a V atom enhances considerably the thermodynamic stability of odd-numbered gold clusters but reduces that of even-numbered systems. The atomic shape has an apparently more important effect on the clusters stability than the electronic structure. Especially, if both atomic shape and electronic condition are satisfied, the resulting cluster becomes particularly stable such as the anion Au₁₂V⁻, which can thus combine with the cation Au⁺ to form a superatomic molecule of the type [Au₁₂V]Au. Numerous lower-lying electronic states of these clusters are very close in energy, in such a way that DFT computations cannot clearly establish their ground electronic states. Calculated results demonstrate the existence of structural isomers with comparable energy content for several species including Au₉V, Au₁₀V, Au₁₃V and Au₁₄V.