Hund’s rule in metal clusters: Prediction of high magnetic moment state of (formula presented) from first-principles calculations

Using ab initio pseudopotential plane wave method and generalized gradient approximation for the exchange and correlation energy, we report the finding of high spin ground state of (formula presented) cluster in accordance with the Hund’s rule of maximum spin at half-filling. It has perfect icosahedral symmetry and a magnetic moment of (formula presented) forming an open shell superatom. Further studies of its interaction with an Al atom have led to an electronically closed shell magic cluster with 1.68 eV highest occupied–lowest unoccupied molecular orbital (HOMO-LUMO) gap such that the added Al atom is incorporated within the cage around the Cu atom.