Stability of Asn [n=4, 8, 20, 28, 32, 36, 60] cage structures

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 Asn cages for sizes 4, 8, 20, 28, 32, 36, and 60 wherein each As atom is threefold 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 As20 is energetically stable against dissociation into As4. We suggest that the Raman spectra might be a means for observing the As20 molecule in gas phase.