Anharmonic properties of double giant dipole resonance
  A systematic microscopic study of the anharmonic properties of the double giant dipole resonance (DGDR) has been carried out, for the first time, for nuclei with mass number $A$ spanning the whole mass table. It is concluded that the corrections of the energy centroid of the $J^{\pi} = 0^+$ and $2^+$ components of the DGDR from its harmonic limit are negative, have a value of the order of few hundred keV and follow an $A^{-1}$ dependence. 
V. Yu. Ponomarev, P. F. Bortignon, R. A. Broglia, and V. V. Voronov