  A new theoretical approach for the calculation of optical properties of complex solutions is proposed. It is based on a dielectric matrix with included small metallic inclusions (less than 3 nm) of spherical shape. We take into account the mutual interactions between the inclusions and the quantum finite-size effects. On the basis of the effective medium model, TDLDA and Kohn-Sham theories, some analytical expressions for the effective dielectric permittivity of the solution are obtained. 
Size-dependent effects in solutions of small metal nanoparticles