Cluster study of Al-Co-Ni decagonal quasicrystal

The electronic structure and atomic arrangement of a decagonal Al-Co-Ni quasicrystal have been investigated in terms of a model unit cluster by using a discrete variational Xα (DV-Xα) cluster calculation. The partial electronic density of states (DOS) and overlap population analysis for local clusters around the constituent transition-metals (TM's) show the energy reduction of both the Co and Ni 3d states but the increase in the anti-bonding character for their TM-Al bonds at the second inner ring TM site of the model cluster in comparison to the most inner ring TM site. Comparing the calculated DOS with the observed valence-band photoelectron and TM Lα X-ray emission spectra, we discuss the occupation at the transition metal sites by Co and Ni.