Electron interaction and the polaron in polymers

Currently, the extended Hubbard model, which is a good approximation only f or narrow-band system, suggests that the width of polaron in polymer is hea vily reduced by the electron-electron interaction. However, the polymers po ssess wide band, so the off-diagonal correlation cannot be neglected. We co nsidered the effects of full electron-electron correlation on the width and the creation energy of polaron in polymer. In the case of strong screening , our results are greatly different from those of Hubbard model. This sugge sts that in polymer, the Hubbard model should be gone beyond.