Calculated electronic structure of icosahedral Al and Al-Mn alloys

Electronic structure calculations on Al and Al-Mn clusters of icosahedral (${\mathrm{I}}_{\mathrm{h}}$) symmetry show important differences compared with such calculations on clusters of cubic (${\mathrm{O}}_{\mathrm{h}}$) symmetry. Anomalously high state densities at ${\mathrm{E}}_{\mathrm{F}}$ and energy dependence proportional to ${\mathrm{E}}^{\mathrm{n}}$, n≥1, characterize the ${\mathrm{I}}_{\mathrm{h}}$ clusters. Highly symmetric molecular-orbital topologies make icosahedral clusters appear like large quasiatoms. Central Mn atoms destabilize ${\mathrm{I}}_{\mathrm{h}}$ clusters.