Self-consistent density-functional calculations of the geometries, electronic structures, and magnetic moments of Ni-Al clusters

We report ab initio molecular dynamics simulations of ${\mathrm{Ni}}_{2},$ ${\mathrm{Al}}_{2},$ ${\mathrm{Ni}}_{13},$ ${\mathrm{Al}}_{13},$ and ${\mathrm{Ni}}_{12}\mathrm{Al}$ clusters using SIESTA, a fully self-consistent density-functional method that employs linear combinations of atomic orbitals as basis sets, standard norm-conserving pseudopotentials and a generalized-gradient approximation to exchange and correlation. Our results for the pure Ni and Al clusters, which are compared with those obtained by other recent ab initio calculations, are in good agreement with available experimental data. For the binary cluster ${\mathrm{Ni}}_{12}\mathrm{Al}$ our calculations show that a distorted icosahedral configuration with the Al atom at the cluster surface is more stable than that with the Al atom located at the central site, a result that clarifies discrepancies between the results of different semiempirical treatments.