The bonding nature of icosahedral clusters of the group III elements

The bonding nature of icosahedral clusters of the group III elements was investigated to obtain the relation between properties of the clusters and their aggregates, i.e., icosahedral boron-rich solids and icosahedral aluminum-based quasicrystals, By means of a molecular orbital method of the bonding nature was evaluated whether it is metallic or covalent type, It is found that the 12-atom icosahedra (B-12 and Al-12) and the 13-atom icosahedra (B-13 and Al-13) show covalent and metallic-type bonding, respectively. Solid state properties of a cluster solid of the group III elements are considered to be profoundly related to the question whether the central icosahedral position is occupied or not. (C) 1997 Academic Press.