Dipole polarizabilities of trimetallic nitride endohedral fullerenes M3N@C2n (M = Sc and Y; 2n = 68–98)

The electronic structures and static dipole polarizabilities of M3N@C2n fullerenes (M = Sc and Y; 2n = 68–98) were studied by using density functional theory. Unlike nonmetal endohedral fullerenes, M3N@C2n show smaller static dipole polarizabilities than the corresponding C2n ones do. It is because the induced electric field of carbon cages is reduced by inserting M3N cluster. The mean dipole polarizabilities of M3N@C2n fullerenes were found to correlate closely to their chemical hardness and electron delocalization volume. The refractive indexes of the face-centered-cubic crystals assembled by M3N@C2n fullerenes were also estimated.