Dissipative Two-Electron Transfer

TL;DR

This paper studies non-equilibrium two-electron transfer in a dissipative environment using a Hubbard model, revealing conditions for concerted versus sequential electron transfer and the effects of interactions and temperature.

Contribution

It introduces a non-perturbative analysis of two-electron transfer dynamics considering electron-electron interactions and dissipation, highlighting conditions for concerted transfer.

Findings

Sequential transfer rates depend non-monotonically on Coulomb interaction differences.

Simultaneous two-electron transfer occurs when Coulomb differences exceed hopping and reorganization energy.

Temperature and bath effects influence the transfer mechanism and rates.

Abstract

We investigate non-equilibrium two-electron transfer in a model redox system represented by a two-site extended Hubbard model and embedded in a dissipative environment. The influence of the electron-electron interactions and the coupling to a dissipative bosonic bath on the electron transfer is studied in different temperature regimes. At high temperatures Marcus transfer rates are evaluated and at low temperatures, we calculate equilibrium and non-equilibrium population probabilities of the donor and acceptor with the non-perturbative Numerical Renormalization Group approach. We obtain the non-equilibrium dynamics of the system prepared in an initial state of two electrons at the donor site and identify conditions under which the electron transfer involves one concerted two-electron step or two sequential single-electron steps. The rates of the sequential transfer depend non-monotonically on the difference between the inter-site and on-site Coulomb interaction which become renormalized in the presence of the bosonic bath. If this difference is much larger than the hopping matrix element, the temperature as well as the reorganization energy, simultaneous transfer of both electrons between donor and acceptor can be observed.