Coating of a layer of Au on Al₁₃: The findings of icosahedral Al@Al₁₂Au₂₀⁻ and Al₁₂Au₂₀²⁻ fullerenes using ab initio pseudopotential calculations

We report results of ab initio pseudopotential calculations on the nanocoating of gold on an icosahedral Al₁₃ cluster and the findings of icosahedrally symmetric endohedral Al@Al₁₂Au₂₀⁻ and empty cage Al₁₂Au₂₀²⁻ compound fullerenes formed of metal atoms. Twelve Al atoms cap the pentagonal faces of a dodecahedral Au₂₀ cage in which each Au atom has three Al atoms and three Au atoms as nearest neighbors. Mixing of Al₁₃ and Au₂₀ magic clusters leads to a large heat of formation of 0.55 eV/atom and high stability of the Al@Al₁₂Au₂₀ compound fullerene. The binding energies of Al₁₂Au₂₀ and Al@Al₁₂Au₂₀ are 3.017 and 3.007 eV/atom, respectively, which are much larger than 2.457 eV/atom for Au₃₂ fullerene, leading to the possibility of their high abundance.