Electromagnetic response of broken-symmetry nano-scale clusters
  A microscopic, non-local response theory is developed to model the interaction of electromagnetic radiation with inhomogeneous nano-scale clusters. The breakdown of classical continuum-field Mie theory is demonstrated at a critical coarse-graining threshold, below which macroscopic plasmon resonances are replaced by molecular excitations with suppressed spectral intensity. 
Ilya Grigorenko, Stephan Haas, A.F.J. Levi