Geometric and electronic structures of new endohedral fullerenes: Eu@C₇₂

The geometric and electronic structures of rare earth metallofullerenes Eu@C₇₂ were investigated using density functional theory (DFT) within a generalized gradient approximation (GGA). The geometric optimization revealed that the most favorable endohedral site for Eu is off-center along the C₂ axis on the σ_v plane pointing to the (5, 5) bond at the fusion of two pentagons. Calculations for electronic structures show that two 6s electrons in Eu transfer to the lowest-unoccupied-molecular orbitals of C₇₂ while 4f electrons remain in Eu.