Description of electron transport dynamics in molecular devices: A time-dependent density functional theoretical approach in momentum space makes it simple

TL;DR

This paper introduces a first-principles TDDFT approach in momentum space for accurately studying electron transport in molecular devices under arbitrary biases, avoiding common approximations.

Contribution

It develops a formally exact, self-energy-free TDDFT method in momentum space that captures all electron transport effects in molecular devices.

Findings

Successfully calculates current in 1D systems

Avoids self-energy and memory terms

Operates beyond the wide-band limit

Abstract

We propose a first-principles time-dependent density functional theoretical (TDDFT) approach in momentum (P) space for quantitative study of electron transport in molecular devices under arbitrary biases. In this approach, the basic equation of motion is a time-dependent integrodifferential equation obtained by Fourier transform of the time-dependent Kohn-Sham (TDKS) equation in spatial coordinate (R) space. It is formally exact and includes all the effects and information of the electron transport in molecular devices. The electron wavefunction is calculated by solving this equation in a closed finite P-space volume. This approach is free of self-energy function and memory term and beyond the wide-band limit (WBL). The feasibility and power of the approach are demonstrated by the calculation of current through one-dimensional (1D) systems.