Comment on ``First-principles treatments of electron transport properties for nanoscale junctions''

We mimic nanorod-based transparent electrodes as random resistor networks (RRN) produced by the homogeneous, isotropic, and random deposition of conductive zero-width sticks onto an insulating substrate. We suppose that the number density (the number of objects per unit area of the surface) of these sticks exceeds the percolation threshold, i.e., the system under consideration is a conductor. We computed the electrical conductivity of random resistor networks vs the number de...

The description of optical properties of subnanometer junctions is particularly challenging. Purely classical approaches fail, because the quantum nature of electrons needs to be considered. Here we report on a novel classical fully atomistic approach, {\omega}FQ, based on the Drude model for conduction in metals, classical electrostatics and quantum tunneling. We show that {\omega}FQ is able to reproduce the plasmonic behavior of complex metal subnanometer junctions with qua...

We present an overview of current-induced effects in nanoscale conductors with emphasis on their description at the atomic level. In particular, we discuss steady-state current fluctuations, current-induced forces, inelastic scattering and local heating. All of these properties are calculated in terms of single-particle wavefunctions computed using a scattering approach within the static density-functional theory of many-electron systems. Examples of current-induced effects i...

We present first-principles calculations on electron transport through Na nanowires at finite bias voltages. The nanowire exhibits a nonlinear current-voltage characteristic and negative differential conductance. The latter is explained by the drastic suppression of the transmission peaks which is attributed to the electron transportability of the negatively biased plinth attached to the end of the nanowire. In addition, the finding that a voltage drop preferentially occurs o...

We study the performance of two different electrode models in quantum transport calculations based on density functional theory: Parametrized Bethe lattices and quasi-one dimensional wires or nanowires. A detailed account of implementation details in both cases is given. From the systematic study of nanocontacts made of representative metallic elements, we can conclude that parametrized electrode models represent an excellent compromise between computational cost and electron...

The electrical transport properties of atomic-scale conductors are reviewed, with an emphasis on the relations of this problem with studies on quantum size effects in metallic clusters. A brief introduction is given of the natural formalism for discussing electron transport in ballistic conductors: the Landauer theory. After introducing the experimental techniques, which are used for studying ballistic point contacts in metals, the experimental observations for the conductanc...

In their letter on the quantum Child-Langmuir law, Ang, Kwan and Lau (Phys. Rev. Lett. 91, 208303 (2003)) include exchange correlation effects within the Kohn-Sham density functional theory and explore numerically the maximum transmitted current in nanogaps. We show here that the calculations are in error as the exchange-correlation component of the chemical potential has been ignored while fixing the boundary conditions for the Hartree potential.

Using the Landauer formulation of transport theory and tight binding models of the electronic structure, we study electron transport through atomic wires that form 1D constrictions between pairs of metallic nano-contacts. Our results are interpreted in terms of electron standing waves formed in the atomic wires due to interference of electron waves reflected at the ends of the atomic constrictions. We explore the influence of the chemistry of the atomic wire-metal contact int...

A new form of gold nanobridges has been recently observed in ultrahigh-vacuum experiments, where the gold atoms rearrange to build helical nanotubes, akin in some respects to carbon nanotubes. The good reproducibility of these wires and their unexpected stability will allow for conductance measurements and make them promising candidates for future applications . We present here a study of the transport properties of these nanotubes in order to understand the role of chirality...

Metal nanowires exhibit a number of interesting properties: their electrical conductance is quantized, their shot-noise is suppressed by the Pauli principle, and they are remarkably strong and stable. We show that many of these properties can be understood quantitatively using a nanoscale generalization of the free-electron model. Possible technological applications of nanowires are also discussed.