Effect of Electrode Orientations on Charge Transport in Alkanedithiol Single-Molecule Junctions

Abstract

Using first-principles calculations based on the density functional theory and the nonequilibrium Green's functions approach, we study the charge transport in Au-alkanedithiol-Au single-molecule junctions with different electrode orientations and molecular lengths. We attribute the recently measured high-/low-conductance in these heterostructures to two distinct electrode orientations, [100] and [111], which can control the electrode-molecule coupling as well as the tunneling strength by way of diverse band structures. Our detailed analysis on the transmission spectra suggests that even a single alkanedithiol junction can serve as a double quantum-dot system to yield tunable quantum interference.

Applicability of the wide-band limit in DFT-based molecular transport calculations

“…Several studies exist in which, for a particular method, the effects of various modeling choices (e.g., system size, basis-set, exchangecorrelation potential, or number of k-vectors) on the accuracy have been investigated. 23,[28][29][30][31][32][33] The present study, however, focuses mainly on comparing different methods on the same system.…”

Effect of gold electrode crystallographic orientations on charge transport through aromatic molecular junctions

“…Long nanowires with lengths from 200 nm to 1 µm [46] can be implemented with 1,1,0 electrodes and exhibit quantised conductance. For electrodes with other orientations, such as 1,0,1 and 1,1,1 , only short wires of length 50 to 200 nm [46] can be formed [7].…”

“…Different electrode orientations having varied band structures can affect the junction conductance and thus result in variable charge flow on the device incident from electrodes. They concluded that molecular junction having Au 1,0,0 orientation provided high conductance, while gold electrodes with 1,1,1 orientation exhibited low conductance in alkanedithiol molecular junctions [7]. In this paper, we extended their work to explore this anisotropic property of electrodes on the electrical conduction through aromatic molecular junction comprising anthracene molecule, a tricyclic alternant hydrocarbon molecule stringed between three different orientations of gold via sulphur linker atoms.…”

“…They concluded that the crystallographic orientations of gold electrodes are of asymmetric nature because of their azimuthal deviations in crystallographic orientations. Later in 2010, Sen and Kaun computed the effect of electrode orientations on charge transport in alkanedithiol junctions and concluded that the electrode orientations can control the tunnelling strength by diverse band structures [7][8][9]. This electrode orientation can be varied by changing the miller indices of the electrode atoms [10].…”

Enhancement of anisotropic magnetoresistance in zigzag graphene nanodevices

“…Essentially, within the DFT-NEGF scheme, the device Hamiltonian and the electronic structure are determined by DFT while the nonequilibrium quantum statistics of the device physics is determined by NEGF [8,9].…”