Exchange-correlation functionals of i-DFT for asymmetrically coupled leads

TL;DR

This paper extends the i-DFT approach to analyze steady-state transport in nanoscale systems with asymmetric lead coupling and voltage bias, providing insights into conductance spectra evolution.

Contribution

It introduces generalized exchange-correlation functionals for asymmetric coupling and bias within the i-DFT framework, advancing the modeling of such systems.

Findings

Conductance spectra change with asymmetry in voltage and coupling.

Symmetric voltage drop can be achieved via a total energy shift.

Generalized functionals improve modeling of asymmetric systems.

Abstract

A recently proposed density functional approach for steady-state transport through nanoscale systems (called i-DFT) is used to investigate junctions which are asymmetrically coupled to the leads and biased with asymmetric voltage drops. In the latter case, the system can simply be transformed to a physically equivalent one with symmetric voltage drop by a total energy shift of the entire system. For the former case, known exchange correlation gate and bias functionals have to be generalized to take into account the asymmetric coupling to the leads. We show how differential conductance spectra of the constant interaction model evolve with increasing asymmetry of both voltage drops and coupling to the leads.