  We investigate the vibrational stability and the electronic structure of the
proposed icosahedral fullerene-like cage structure of B80 [Szwacki, Sadrzadeh,
and Yakobson, Phys. Rev. Lett. {\bf 98}, 166804 (2007)] by an all electron
density functional theory using polarized Gaussian basis functions containing
41 basis functions per atom. The vibrational analysis of B$_{80}$ indicates
that the icosahedral structure is vibrationally unstable with 7 imaginary
frequencies. The equilibrium structure has $T_h$ symmetry and a {\em smaller}
gap of 0.96 eV between the highest occupied and lowest unoccupied molecular
orbital energy levels compared to the icosahedral structure. The static dipole
polarizability of B$_{80}$ cage is 149 \AAA and the first ionization energy is
6.4 eV. The B$_{80}$ cage has rather large electron affinity of 3 eV making it
useful candidate as electron acceptor if it is synthesized. The infra-red and
Raman spectra of the highly symmetric structure are characterized by a few
absorption peaks.
