In this thesis we
introduce a model for electron transfer in symmetric donor-bridge-acceptor
(DBA) complexes with electronic coupling to nuclear bridge modes, using the
Redfield formulation. We investigate the effect of a thermal bath on the
electronic dynamics in terms of the bath temperature, spectral density and the
electronic nuclear coupling strength for tunneling through the bridge. We study
the validity of Redfield simulation and we demonstrate that the transport
mechanism through the molecular bridge is controlled by the location of the
electronic nuclear coupling term along the bridge. As the electronic nuclear
coupling term is shifted from the donor/acceptor-bridge contact sites into the inner
bridge sites, the mechanism changes from kinetic transport (incoherent,
thermally activated, bridge-length independent) to coherent tunneling oscillations.
We introduce a kinetic scheme for defining rate constants in the kinetic
regime. This study joins earlier works aiming to explore the factors which
control the mechanism of electronic transport through molecular bridges and
molecular wires. We show that even local coupling to the thermal bath can
induce pure dephasing leading to coherent
mechanism.
