Dynamics of polarons in conjugated polymers: An adaptive time-dependent density-matrix renormalization-group study

Abstract

The motion of polarons, which serve as charge carriers in conjugated polymers, is of fundamental importance for understanding transport properties of organic optoelectronic devices. We investigate the dynamics of a charged polaron in the presence of both electron-phonon and electron-electron interactions under the influence of an external electric field, which is modeled by the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model supplemented with a Hubbard on-site repulsion term. For this many-body dynamical evolution problem, we develop an adaptive time-dependent density matrix renormalization group ($t$-DMRG) method in combination with a Newtonian equation of motion for atomic displacements. Our results show that the velocity of the polaron is suppressed by the on-site Coulomb interaction $U$. The polaron moves with a supersonic velocity, about four times the sound velocity at the small $U$ limit, and approaches the sound velocity at the large $U$ limit. Furthermore, the dependence of the polaron velocity and the polaron effective mass on the lattice structures are discussed.