Enhanced stability of magic clusters: A case study of icosahedralAl12X,X=B, Al, Ga, C, Si, Ge, Ti, As

We present results of the electronic structure and stability of some forty valence electron icosahedral ${\mathrm{Al}}_{12}$X (X=B, Al, Ga, C, Si, Ge, Ti, and As) clusters within the local spin density functional theory. It is shown that the stability of the ${\mathrm{Al}}_{13}$ cluster can be substantially enhanced by proper doping. For neutral clusters, substitution of C at the center of the icosahedron leads to the largest gain in energy. However, ${\mathrm{Al}}_{12}$ ${\mathrm{B}}^{\mathrm{-}}$ is the most strongly bound in this family. These results are in agreement with the recent experiments which also find ${\mathrm{Al}}_{12}$ ${\mathrm{B}}^{\mathrm{-}}$ to be highly abundant.