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Electronic structures, spontaneous polarization, dynamical and nonlinear optical (NLO) properties of polar oxide ZnSnO(3) with LiNbO(3) (LN)-type structure have been investigated in the framework of density functional theory. By analyzing the Born effectives of LN-type ZnSnO(3), we find that Z* of Zn atoms show relatively large anomalous behavior. The spontaneous polarization is attributed to the large displacement of Zn atoms because of the mixed ionic-covalent character between the Zn-O bonds. The optical dielectric tensor is nearly the same; however the static dielectric tensor shows strongly anisotropy. Furthermore, the nonlinear optical properties are calculated by using 2n + 1 theorem applied to an electric-field dependent energy functional. The large dielectric constants and NLO susceptibilities indicate that the LN-type ZnSnO(3) would be a candidate as a high-performance dielectric and nonlinear optical material.

Based on a theoretical model proposed for quasi-one-dimensional organic polymer ferromagnets, the spin configuration of vr electrons in a~-conjugated carbon chain with a single and two side radicals, which contains unpaired electrons, is investigated.The strong electron-phonon interaction and electron-electron interaction in the one-dimensional system are taken into account self-consistently. It is found that around the unpaired electrons there appears a~-electron spin-polarization cloud with alternation of the sign and the amplitude of the spin density extending over a certain distance, which reduces rapidly with the increasing of electron-phonon coupling. In order to obtain ferromagnetic order in this kind of material, the number of carbon atoms, which is intermittent between two neighbor side radicals, should be odd. It is shown that the~-orbital alternation will result in a Peierls transition which stabilizes the magnetic order.