  Bonding, electric (hyper)polarizability, vibrational and magnetic properties
of heterofullerene ${\rm C}_{48}{\rm B}_{12}$ are studied by first-principles
calculations. Infrared- and Raman-active vibrational frequencies of ${\rm
C}_{48}{\rm B}_{12}$ are assigned. Eight $^{13}$C and 2 $^{11}$B NMR spectral
signals of ${\rm C}_{48}{\rm B}_{12}$ are characterized. The first-order
hyperpolarizability in ${\rm C}_{48}{\rm B}_{12}$ is zero because of the
inversion symmetry. The average second-order hyperpolarizability of ${\rm
C}_{48}{\rm B}_{12}$ is about 180% larger than that of ${\rm C}_{60}$. Our
results suggest that ${\rm C}_{48}{\rm B}_{12}$ is also a candidate for
photonic and optical limiting applications because of the enhanced third-order
optical nonlinearities.
