Long wavelength limit of two dimensional photonic crystals
  We solve {\bf analytically} the multiple scattering (KKR) equations for the two dimensional photonic crystals in the long wavelength limit. Different approximations of the electric and magnetic susceptibilities are presented from a unified pseudopotential point of view. The nature of the so called plasmon-polariton bands are clarified. Its frequency as a function of the wire radius is discussed. 
S. T. chui and Z. F. Lin