Resonant inelastic tunneling in molecular junctions

Abstract

Within a phonon-assisted resonance level model we develop a self-consistent procedure for calculating electron transport currents in molecular junctions with intermediate to strong electron-phonon interaction. The scheme takes into account the mutual influence of the electron and phonon subsystems. It is based on the 2 nd order cumulant expansion, used to express the correlation function of the phonon shift generator in terms of the phonon momentum Green function. Equation of motion (EOM) method is used to obtain an approximate analog of the Dyson equation for the electron and phonon Green functions in the case of many-particle operators present in the Hamiltonian. To zero-order it is similar in particular cases (empty or filled bridge level) to approaches proposed earlier. The importance of self-consistency in resonance tunneling situations (partially filled bridge level) is stressed. We confirm, even for strong vibronic coupling, a previous suggestion concerning the absence of phonon sidebands in the current vs. gate voltage plot when the source-drain voltage is small 35 .

Phonon-assisted Andreev reflection in a hybrid junction based on a quantum dot

“…Moreover, splitting of the phonon satellite resonances due to AR processes is found to appear in case of nonvanishing effective ondot Coulomb correlations. The results obtained for the equilibrium situation prove that the F-QD-S hybrid system exhibits similar behavior as observed earlier for tunnelling through N/F-QD-N/F type junctions [10][11][12], i.e. such features as the polaron shift, suppression of the linear conductance with increasing on-dot electron-phonon interactions as well as the lack of phonon satellites in the linear conductance may be predicted.…”

“…The latter appears as a result of the assumed approximation for the Green function given by equation (15). As stated previously (see [10][11][12]) such an approach applied to mesoscopic QD-based systems, where phonons interact with tunneling carriers allows to include both electron as well as hole contributions in the Green function correlators. Thus, the discussion presented here is in contrast to earlier studies on phonon-assisted AR transmission through hybrid F-QD-S or N-QD-S junctions (see e.g.…”

“…Moreover, taking into account the results of previous discussion on different approximations used to evaluate the Green functions for the dot interacting with phonons (for details see e.g. [10][11][12]), we consider the effects due to both the electron and hole transmission. Thus at zero temperature and for the electron-hole symmetry our approach results in appearance of the phonon emission satellites on both sides of the main elastic peaks in spectral function.…”

Role of molecular electronic structure in inelastic electron tunneling spectroscopy:O2on Ag(110)

“…If the average number of excited modes is on the order of 1, then the SCBA gives a very good account of the vibrational excitation even in the case of extraordinary vibronic effects. 43 Approaches going beyond SCBA are available 45,46 and are necessary for exploring realistic situations where the electron-vibration coupling is strong enough to excite several overtones. Figure 8 shows the results of the SCBA for the O-O stretch mode.…”

Kinetic control of the current through a single molecule

“…Our main objective for using such a simplified description is to derive analytic expressions for the current which can be directly compared with those following from the scattering approach. Corrections related to important electron-vibration interactions result in some fine structures in the I-V-curves [16,19,20,22,26,[37][38][39][40] and are not considered here further. Therefore, the derived analytic results describe the coarsened I-V characteristics of the LMR-device with a single active MO.…”