Long-range Coulomb interaction effects on polarons in conjugated polymers

• We have studied the influence of e–e interactions on polaron dynamics.
• e–e Interactions include on-site (U) and long-range Coulomb interactions (V).
• Saturated velocity and critical dissociation field vary non-monotonically with V.
• A polaron takes on the most localized configuration at a critical strength of V.
• Competition between U and V leads to the non-monotonic relationship.

Combining the Su–Schrieffer–Heeger and Pariser–Parr–Pople model (SSH+PPP), we have studied the influence of electron–electron interactions on the motion and dissociation of a polaron in the presence of an electric field, with emphasis on the long-range Coulomb interactions. The multiconfigurational time-dependent Hartree–Fock (MCTDHF) formalism was used to compute the electron–electron interactions. How the saturated velocity and the critical dissociation electric field of the polaron are related to the on-site Coulomb repulsion and long-range Coulomb interactions has been investigated. It was found that the on-site Coulomb interaction does not favor the motion of a polaron. There is a critical strength of the long-range Coulomb interaction for which the polaron takes on the most localized configuration. Comparing with the results obtained using the extended Hubbard model, we found that competition between the long-range Coulomb interactions and the on-site Coulomb interaction leads to a non-monotonic dependence of both the saturated velocity and the critical dissociation electric field on the long-range Coulomb interactions.

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