Effects of e-e interactions on the dynamics of polarons in conjugated polymers

Abstract

Combining the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and the extended Hubbard model (EHM), we investigate the effect of electron-electron interactions on the dynamics of a charged polaron in a conjugated polymer chain, by using a nonadiabatic dynamical method. Both the localization and the velocity of the polaron will vary with the on-site Coulomb interactions U and the nearest-neighbor interactions V . It is found that the local extremum of the stationary velocity of the polaron occurs at U ≈ 2 V (U, V > 0). Additionally, the relation between the velocity and the lattice structure of the polaron is shown qualitatively.

Dynamical Simulations of Polaron Transport in Conjugated Polymers with the Inclusion of Electron−Electron Interactions

“…Di et al 's UHF calculations [23] and Zhao et al 's recent adaptive TDDMRG results [48], but not in accordance to our recent studies on charged soliton transport, in which we found that charged soliton transport velocity is non-monotonic in U [49]. The different behaviors of charge carrier transport with U increasing is due to the different characteristics of charged solitons and polarons.…”

“…In order to improve this situation, Di et al have considered extended Hubbard model (EHM) combined with the SSH model and investigated the dynamics of polarons within this model at the level of an unrestricted Hartree-Fock (UHF) approximation. [23] They found that the localization of the polaron is enhanced and the stationary velocity of the polaron is decreased by both the on-site repulsions U and the nearest-neighbor interactions V . Furthermore, they found that the local extremum of the stationary velocity of the polaron appears at U ≈ 2V .…”

Long-range Coulomb interaction effects on polarons in conjugated polymers

“…The more localized a polaron is the larger is its effective mass. As a result, the saturated velocity decreases monotonically with increasing U, which is in agreement with the results obtained by other theoretical calculations [16][17][18]. Therefore, we can conclude that the on-site Coulomb interaction tends to reduce the speed of a polaron.…”

“…[18]. Di et al also found, using the unrestricted Hartree Fock approximation, that the velocity decreased monotonically with increasing nearest-neighbor interactions when U was fixed [16]. In comparison with the extended Hubbard model, the SSH+PPP model that we have adopted also includes long-rang Coulomb interactions.…”

“…e l s e v i e r . c o m / l o c a t e / o r g e l unrestricted Hartree-Fock approximation, Di et al found that the localization of the polaron was strengthened and the saturated velocity of the polaron was decreased by both on-site Coulomb repulsion, U, and the nearest-neighbor interactions, V [16]. Recently, Zhao and coworkers have investigated the dependence of the velocity on the on-site Coulomb interaction U using an adaptive time-dependent density matrix renormalization group method.…”