The ultrafast hole dynamics triggered by the photoexcitation of molecular targets is a highly correlated process even for those systems, like organic molecules, having weakly ground state. We here provide unifying framework and numerically efficient matrix formulation state-of-the-art non-equilibrium Green's function (NEGF) methods second-Born as well $GW$ $T$-matrix without {\em with} exchange...

Abstract The paper presents a device simulator for computing transport characteristics from first principles. developed computer program effectively performs large-scale parallel calculation of quasi-one-dimensional quantum in realistic nanoscale devices with thousands atoms the cross section area channel. Our is based on real-space Kohn–Sham Hamiltonian density functional theory and improved n...

In this paper, we present the mathematical and implementation details of an ab initio method for calculating spin-polarized quantum transport properties of atomic scale spintronic devices under external bias potential. The method is based on carrying out density functional theory (DFT) within the Keldysh non-equilibrium Green's function (NEGF) formalism to calculate the self-consistent spin den...

This article describes a model for Resonant Tunneling Diodes (RTDs) implemented within ATLAS framework. The model is based on a self-consistent solution of Poisson and Non-Equilibrium Green’s Function (NEGF) equations with an effective mass Hamiltonian. Simulation results are presented for generic GaAs and SiGe RTDs.

D.G. Walker Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212, USA Abstract Variably spaced semiconductor superlattice (VSSL) have exhibited superior electron mobility and rectification because of electronic level alignment. We have investigated the thermoelectric properties of VSSL structures using a self-consistent non-equilibrium Green’s function (NEGF) ...

The non-equilibrium Green's function (NEGF) formalism provides a sound conceptual basis for the development of atomic level quantum mechanical simulators that will be needed for nanoscale MOS devices of the future. However, this formalism is based on concepts that are unfamiliar to most device physicists and as such remains relatively obscure. In this paper we try to achieve two objectives : (1...

In this paper, the performance of a CNT-JLTFET under different values of torsional strains of 0, 3, and 5 degrees has been investigated. Simulation has been carried out using non-equilibrium Green’s function (NEGF) formalism in the mode-space approach and in the ballistic limit. The simulation results indicate that, under torsional strain, an increase occurs in the energy band-gap, and thus the...

Through the Non-Equilibrium Green’s Function (NEGF) formalism, quantumscale device simulation can be performed with the inclusion of electron-phonon scattering. However, the simulation of realistically sized devices under the NEGF formalism typically requires prohibitive amounts of memory and computation time. Two of the most demanding computational problems for NEGF simulation involve mathemat...

By applying tensile local uniaxial strain on 5 nm of drain region and compressive local uniaxial strain on 2.5 nm of source and 2.5 nm of channel regions of graphene nanoribbon tunneling field-effect transistor (GNR-TFET), we propose a new bandgap-engineered (BE) GNR-TFET. Simulation of the suggested device is done based on non-equilibrium Green’s function (NEGF) method by a mode-space approach...

The central computation in atomistic, quantum transport simulation consists in solving the Schrödinger equation several thousand times with non-equilibrium Green’s function (NEGF) equations. In the NEGF formalism, a numerical linear algebra problem is identified related to the computation of a sparse inverse subset of general sparse unsymmetric matrices. The computational challenge consists in ...