A time-dependent momentum-space density functional theoretical approach for electron transport dynamics in molecular devices

Abstract

We propose a time-dependent density functional theoretical (TDDFT) approach in momentum (\mathcal{P} ) space for the study of electron transport in molecular devices under arbitrary biases. The basic equation of motion, which is a time-dependent integrodifferential equation obtained by Fourier transform of the time-dependent Kohn-Sham equation in spatial coordinate (\mathcal{R} ) space, is formally exact and includes all the effects and information of the electron transport in the molecular devices. The electron wave function is calculated by solving this equation in a finite \mathcal{P} -space volume. This approach is free of self-energy function and memory term related to the electrodes in the \mathcal{R} space and beyond the wide-band limit (WBL). The feasibility and power of the approach are demonstrated by the calculation of current through one-dimensional systems.