The Role of the Exchange-Correlation Potential in ab initio Electron Transport Calculations

TL;DR

This paper examines how the choice of exchange-correlation potential impacts ab initio electron transport calculations, highlighting significant effects on conductance accuracy due to energy gap changes and self-interaction errors.

Contribution

It introduces a method to assess the influence of different exchange-correlation potentials on electron transport, emphasizing the importance of these factors for precise quantum conductance predictions.

Findings

Energy gap changes cause about an order of magnitude error in conductance.

Self-interaction errors can lead to two orders of magnitude inaccuracies.

The impact varies with coupling strength and charge transfer.

Abstract

The effect of the exchange-correlation potential in ab initio electron transport calculations is investigated by constructing optimized effective potentials (OEP) using different energy functionals or the electron density from second-order perturbation theory. We calculate electron transmission through two atomic chain systems, one with charge transfer and one without. Dramatic effects are caused by two factors: changes in the energy gap and the self-interaction error. The error in conductance caused by the former is about one order of magnitude while that caused by the latter ranges from several times to two orders of magnitude, depending on the coupling strength and charge transfer. The implications for accurate quantum transport calculations are discussed.