Average dielectric function, theories

An ansatz for treating the resultant optical properties is to treat the shell using MG theory to yield an approximate average dielectric function for the shell, and then to use this function in the core-shell geometry. The predictions of this model are shown in Fig. 8. A fixed latex or silica core of 50 nm is shown surrounded by a 5 nm shell of Au Si02 where the Au volume fraction is varied. The medium is taken to be water for simplicity. 

The province of conventional dielectric measurements is here taken to be the determination of the relations of the polarization E and current density J. to the electric field in the macroscopic Maxwell equations. Proper theory should account for these relations in condensed phases as a function of state variables time dependence of applied fields and molecular parameters by appropriate statistical averaging over molecular displacements determined by the equations of motion in terms of molecular forces and fields. Simplifying assumptions and approximations are of course necessary. One kind often made and debated is use of an effective or mean local field at a molecule rather than the sum of microscopic... 

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