Solid-state approach to the modelling of the host-guest optical systems

In the present work the influence of an organic host on the optical properties of a guest chromophore is examined. Two different chromophores have been chosen, namely a silicon carbide (SiC) nanograin with size 1.9 nm and the 9-(2,3-epoxypropyl)carbazole (EPK) which are inorganic and organic molecules, respectively. The SiC was embedded into a poly(methyl methacrylate) matrix. EPK molecules were investigated in epoxy resin. The considered systems were built using molecular dynamic simulations methods. UV-absorption spectra and first order nonlinear optical hyperpolarizability /spl beta//sub zzz//sup SHG/ for the considered host-guest systems were calculated at semi-empirical level. In both systems the effect of the local field on the optical properties was taken into account. The electronic properties of chromophores change under the influence of the host material. The most important changes can be observed for nonlinear optical properties rather than for linear ones. Additionally it was found that polymer background reconstructs the surface of the SiC nanograin.