Theoretical study of electrical conduction through a molecule connected to metallic nanocontacts

Abstract

We present a theoretical study of electron transport through a molecule connected to two metallic nanocontacts. The system investigated is 1,4 benzenedithiolate (BDT) chemically bonded to two Au contacts. The surface chemistry is modeled by representing the tips of the Au contacts as two atomic clusters and treating the molecule-cluster complex as a single entity in an extended Hückel tight binding scheme. We model the tips using several different cluster geometries. An ideal lead is attached to each cluster, and the lead to lead transmission is calculated. The role of the molecule-cluster interaction in transport is analyzed by using single channel leads. We then extend the calculations to multi-channel leads that are a more realistic model of the tip's environment. Using the finite-voltage, finite temperature Landauer formula, we calculate the differential conductance for the different systems studied. The similarities and differences between the predictions of the present class of models and recent experimental work are discussed.

Nonlinear conductance in molecular devices: Molecular length dependence

“…The eigenstates of the combined system become the scattering states which are Bloch-wavelike in the electrode and molecular orbital-like in the molecule. 33 The more delocalized the state is, more spreading the corresponding transmission peak shows. In Fig.3 we compare the transmission spectra of the coupled dtb system with the OPV3 system at zero bias.…”

Molecular Wire Junctions: Tuning the Conductance

“…The interaction between the molecule and the electrodes is arbitrary; for example, it could be taken from the Newns/Anderson description, 21,26 which represents the metal as a one-dimensional tight binding band. The Landauer conductance can then be written [14][15][16][17][18][19][20][21]27 where is the quantum unit of conductance and where is the transmission probability. Here G is the molecular Green's function, and ∆ is the imaginary part of the molecular selfenergy due to interaction with the electrode.…”

“…In the low voltage regime at low temperatures, conductance is successfully discussed in terms of elastic scattering, following the Landauer picture developed for mesoscopic semiconductor structures. Several different formulations, [14][15][16][17][18][19][20] based on the Landauer formula itself or an equivalent Lippman-Schwinger scattering formalism, have been developed and utilized.…”

Electron transport in nanotube–molecular-wire hybrids

“…The coupling of the molecular complex to the environment as well as its intrinsic ability to convey charge are equally important factors. Hence, whereas the molecular character has been the main focus [8][9][10], the precise nature of the contact and its implications has also become a topic of investigation [11,12].…”