Eur. Phys. J. B (2013) 86: 131
https://doi.org/10.1140/epjb/e2013-31089-1

Regular Article

Nonlinear electronic transport in nanoscopic devices: nonequilibrium Green’s functions versus scattering approach

¹ Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, Brazil
² Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, Brazil

^a e-mail: alexis@if.ufrj.br

Received: 4 December 2012
Published online: 4 April 2013

Abstract

We study the nonlinear elastic quantum electronic transport properties of nanoscopic devices using the nonequilibrium Green’s function (NEGF) method. The Green’s function method allows us to expand the I-V characteristics of a given device to arbitrary powers of the applied voltages. By doing so, we are able to relate the NEGF method to the scattering approach, showing their similarities and differences and calculate the conductance coefficients to arbitrary order. We demonstrate that the electronic current given by NEGF is gauge invariant to all orders in powers of V, and discuss the requirements for gauge invariance in the standard density functional theory (DFT) implementations in molecular electronics. We also analyze the symmetries of the nonlinear conductance coefficients with respect to a magnetic field inversion and the violation of the Onsager reciprocity relations with increasing source-drain bias.