Bipolaron dynamics in nearly degenerate quasi-one-dimensional polymers

We study a nondegenerate conjugated polymer by means of a modified Su-Schrieffer-Heeger-type model Hamiltonian. Analytical solutions are presented for the ground state and dynamic equations are solved numerically. We present solutions representing a bipolaron oscillating between two stages (a kink-antikink pair and a bound-polaron pair). We show that the creating of such a dipolaron can be energetically favorable in the case of either doping or photoexcitation. Our results compare well with the experimental photoluminescence spectrum of cis-(CH${)}_{\mathrm{x}}$.