Superexchange coupling and non-nearest-neighbor interactions in electron transfers

Non-nearest-neighbor interactions in the problem of electron transfer via superexchange are considered. In particular, second-neighbor coupling in a finite disordered chain and exponential coupling in an infinite periodic chain are investigated in detail. Inclusion of these interactions is formulated through a renormalization of the energies as well as of the coupling matrix elements which are constructed by a simple recursive scheme. The form of the extended McConnell formula is then applicable. It is shown that, under certain conditions, the effective coupling between the donor and acceptor sites may suffer large changes