Bound states in ab initio approaches to quantum transport: A time-dependent formulation

TL;DR

This paper investigates how bound electrons influence quantum transport using a time-dependent approach combining Cini's partition-free method with TDDFT, revealing oscillatory behaviors and potential new conduction channels.

Contribution

It introduces a novel time-dependent formulation for quantum transport that explicitly accounts for bound states, highlighting effects overlooked by steady-state models.

Findings

Bound states cause persistent oscillations in current and density.

Oscillations in the effective potential can lead to new conduction pathways.

Steady-state approaches may miss important dynamical effects.

Abstract

In this work we study the role of bound electrons in quantum transport. The partition-free approach by Cini is combined with time-dependent density functional theory (TDDFT) to calculate total currents and densities in interacting systems. We show that the biased electrode-device-electrode system with bound states does not evolve towards a steady regime. The density oscillates with history-dependent amplitudes and, as a consequence, the effective potential of TDDFT oscillates too. Such time dependence might open new conductive channels, an effect which is not accounted for in any steady-state approach and might deserve further investigations.