Electronic coupling for charge transfer in donor–bridge–acceptor systems. Performance of the two-state FCD model
Electronic coupling is a key parameter that determines the rate of electron transfer reactions and electrical conductivity of molecular wires. To examine the performance of a two-state approach based on the orthogonal transformation of adiabatic states to diabatic states, we compare the effective donor–acceptor coupling VDA computed with three different approaches in model donor–bridge–acceptor (D–B–A) systems. It is found that VDA derived with the two-state method accounts properly for both the direct and superexchange interactions. The approach becomes, however, less accurate with the increasing energy difference of the donor and acceptor states. We suggest a simple diagnostic to identify the situation when the estimated coupling might be inaccurate and consider how to improve the performance of the two-state scheme in such a case.
- This article is part of the themed collection: Electron Transfer Theory