A computational investigation of aluminum-doped germanium clusters by density functional theory study

We report a computational study of the aluminum doped germanium clusters GenAl (n = 1–9). The molecular geometries and electronic structures of the GenAl clusters are investigated systematically using quantum calculations at the B3LYP level with the 6-311G(d) basis sets. The growth pattern behaviors, stabilities, electronic properties, and magnetic moments of these clusters are discussed in detail. Obviously different growth patterns appear between small and larger Al-doped germanium clusters, the optimized equilibrium geometries trend to prefer the close-packed configurations for Al-doped germanium clusters up to n = 9. The size dependence of cluster average binding energies per atom (Eb/atom), second-order differences of total energies (Δ2E), fragmentation energies (Ef) and HOMO–LUMO gaps of Gen+1 and GenAl (n = 1–9) clusters are studied. The stability results show that Gen+1 cluster possess relatively higher stability than GenAl cluster. Furthermore, the investigated highest occupied molecular orbital-lowest unoccupied molecular orbital gaps indicate that the Gen+1 and GenAl clusters have different HOMO–LUMO gap. In addition, the calculated vertical ionization potentials and vertical electron affinities confirm the electric properties of Gen+1 and GenAl clusters. Besides, the doping of Al atom also brings the decrease as the cluster sizes increase for atomic magnetic moments (μb).