Site specific atomic polarizabilities in endohedral fullerenes and carbon onions

We investigate the polarizability of trimetallic nitride endohedral fullerenes by partitioning the total polarizability into site specific components. This analysis indicates that the polarizability of the endohedral fullerene is essentially due to the outer fullerene cage and has insignificant contribution from the encapsulated unit. Thus, the outer fullerene cages effectively shield the encapsulated clusters and behave like Faraday cages. The polarizability of endohedral fullerenes is slightly smaller than the polarizability of the corresponding bare carbon fullerenes. The application of the site specific polarizabilities to C-60@C-240 and C-60@C-180 onions shows that, compared to the polarizability of isolated C-60 fullerene, the encapsulation of the C-60 in C-240 and C-180 fullerenes reduces its polarizability by 75% and 83%, respectively. The differences in the polarizability of C-60 in the two onions is a result of differences in the bonding (intershell electron transfer), fullerene shell relaxations, and intershell separations. The site specific analysis further shows that the outer atoms in a fullerene shell contribute most to the fullerene polarizability. (C) 2015 AIP Publishing LLC.