First-principles calculations of the structural, electronic, vibrational and magnetic properties of C_{60} and C_{48}N_{12}: a comparative study

In this work, we perform first-principles calculations of the structural, electronic, vibrational and magnetic properties of a novel ${\rm C}{48}{\rm N}{12}$azafullerene\mathrm{.}Fullgeometricaloptimizationshowsthat${\rm C}{48}{\rm N}{12}$ is characterized by several distinguishing features: only one nitrogen atom per pentagon, two nitrogen atoms preferentially sitting in one hexagon, ${\mathrm{S}}_6$ symmetry, 6 unique nitrogen-carbon and 9 unique carbon-carbon bond lengths. The highest occupied molecular orbital of ${\rm C}{48}{\rm N}{12}$isadoublydegeneratelevelof$a_{g}$ symmetry and its lowest unoccupied molecular orbital is a nondegenerate level of $a_u$ symmetry. Vibrational frequency analysis predicts that ${\rm C}{48}{\rm N}{12}$ has in total 116 vibrational modes: 58 infrared-active and 58 Raman-active modes. ${\mathrm{C}}_{48}{\mathrm{N}}_{12}$ is also characterized by 8 ${}^{13}\mathrm{C}$ and 2 ${}^{15}\mathrm{N}$ NMR spectral signals. Compared to ${\rm C}{60}$,${\rm C}{48}{\rm N}_{12}$ shows an enhanced third-order optical nonlinearities which implies potential applications in optical limiting and photonics.