  Considering the interband correlation, we present a generalized
multiple-scattering approach of Green's function to investigate the effects of
electron-impurity scattering on the density of states in silicene. The
reduction of energy gaps in the case of relatively high chemical potential and
the transformation of split-off impurity bands into band tails for low chemical
potential are found. The dependency of optical conductivity on the impurity
concentration is also discussed for frequency within the terahertz regime.
