  We present all-electron density functional study of the geometry, electronic
structure, vibrational modes, polarizabilities as well as the infrared and
Raman spectra of fullerene-like arsenic cages. The stability of As$_n$ cages
for sizes 4, 8, 20, 28, 32, 36, and 60 wherein each As atom is three-fold
coordinated is examined. We find that all the cages studied are vibrationally
stable and while all the clusters are energetically stable with respect to
isolated arsenic atoms, only As$_{20}$ is energetically stable against
dissociation into As$_4$. We suggest that the Raman spectra might be a means
for observing the As$_{20}$ molecule in gas phase.
