Non-equilibrium Green’s function formalism (NEGF) by employing timedependent (TD) perturbation theory is used to solve the electronic equations of motion of model systems under potential biasing conditions. The time propagation is performed in the full frequency domain of the two time variables representation. We analyze transient aspects of the resulting conductance under effects of applied di...

The effects of layer thickness and periodicity on thermoelectric properties of Si/Ge superlattice materials are studied through a non-equilibrium Green’s function (NEGF) computational approach. Results show an independence of Seebeck coefficient for increasing the number of superlattice periods. Additionally, a critical layer thickness is obtainable to achieve a favorable transmission spectrum ...

Using the non-equilibrium Green's function (NEGF) formalism within the sequential regime, we studied ultrahigh spin thermopower and pure spin current in single-molecule magnet(SMM), which is attached to nonmagnetic metal wires with spin bias and angle (θ) between the easy axis of SMM and the spin orientation in the electrodes. A pure spin current can be generated by tuning the gate voltage and ...

We investigate the effect of edge states on the transport properties of pentacene–graphene nanojunctions on the basis of DFT and NEGF formalism. The calculations reveal that strong interaction between pentacene and zigzag GNR leads to edge-induced transmission channels at the Fermi region which controls the low-bias current. Effects of substitution by electron withdrawing and donating groups on...

Based on generalized quantum Langevin equations for the tight-binding wave function amplitudes and lattice displacements, electron and phonon quantum transport are obtained exactly using molecular dynamics (MD) in the ballistic regime. The electron-phonon interactions can be handled with a quasi-classical approximation. Both charge and energy transport and their interplay can be studied. We com...

We overview the nonequilibrium Green function combined with density functional theory (NEGF-DFT) approach to modeling of independent electronic and phononic quantum transport in nanoscale thermoelectrics with examples focused on a new class of devices where a single organic molecule is attached to two metallic zigzag graphene nanoribbons (ZGNRs) via highly transparent contacts. Such contacts ma...

A three-dimensional full band simulator for nanowire field-effect transistors (FETs) is presented in this thesis. At the nanometer scale the classical drift-diffusion transport theory reaches its limits; quantum transport (QT) phenomena govern the motion of electrons and holes. The development of a QT simulator requires the assembly of several physical models and the choice of appropriate simpl...

We establish well-defined limits in which the time-dependent electronic currents across a molecular junction subject to a fluctuating environment can be quantitatively captured via the Landauer steady-state approximation. For this, we calculate the exact time-dependent non-equilibrium Green's function (TD-NEGF) current along a model two-site molecular junction, in which the site energies are su...

for an Invited Paper for the MAR06 Meeting of The American Physical Society Conductance Through Single Organometallic Molecules1 HAROLD U. BARANGER, Duke University We have undertaken ab initio calculations of the conductance and I-V curve of a variety of single molecules bridging two metallic leads. The method adopted is a non-equilibrium Green function (NEGF) approach to transport combined wi...