The electron.. electron interactions and the creation energy of a soliton in highly conducting polymers were calculated by using a correlated--basis-function method with a general screening Coulomb potential within the Kronig. Penny. model framework. Our results showed that even when the electron-electron interactions are considered，solitons are still the main charge carriers. The strong long-range electron-electron interaction is seen to reduce the creation energy of a soliton. A comparison with results based on the Hubbard model has been made. The 1imitations of the Hubbard model in this application were discussed.

Instead of spin electrons or holes, the carriers in polymers are supposed to be spin polarons or spinless bipolarons. Based on the spin diffusion theory and Ohm's law, we studied spin-polarized injection into organic polymers. It was obtained that only spin polarons are responsible for the current spin polarization in a ferromagnetic (FM)/organic system. Effects of the conductivity matching and the interfacial resistances on the current spin polarization were discussed.

The ground and excited state energies of the two-dimensional D−centre have been calculated, respectively, as a function of magnetic field. The critical magnetic field values at which the excited states change from unbound to bound have been found. The optical transition between two bound states is discussed. Numerical results with the hyperspherical approach are in good agreement with those obtained through other intensive numerical methods and those obtained through experiments.

The electronic structure of diblock copolymers consisting of poly (p-phenylene) and polyacetylene were studied in the framework of an inter-component coupling model. It was found that the band gaps could be tuned by the proportion of the homopolymers. The interfacial coupling between the components also affected the band gaps obviously. Localized states and hybridized states appeared in copolymers due to the interactions between the homopolymers. The doped charges accumulated in its one segment of a copolymer. The accumulation condition is discussed.

In the framework of the tight-binding model, the effects of longitudinal as well as transverse coupling between polyacetylene chains with different lengths and the electron–electron interactions on excitations have been studied. A new spinless charged polaronic excitation (q=±e; s=0) was obtained due to the transverse interchain coupling, which is different from the general magnetic polaron (q=±e; s=1/2) obtained in the perfect one-dimensional model. Due to its end positioning, a polaron is more easily stimulated energetically in a longer chain than in a shorter one, and it can hop to the longer chains nearby via either transverse or longitudinal interchain coupling. In addition, the transverse coupling decreases the energy of creation of a polaron. Considering the strong electron–electron interactions and the end positioning of chains in actual materials, we concluded that the one-dimensional model of conducting polymers is fairly appropriate in certain circumstances.