Determination of complex absorbing potentials from the electron self-energy

TL;DR

This paper presents a method to derive energy-independent complex potentials from the electron self-energy, enabling improved modeling of electron transport in molecular systems with better treatment of reservoir couplings.

Contribution

It introduces a prescription to construct energy-independent, non-local complex potentials from the self-energy for use in electron transport calculations.

Findings

Excellent agreement with exact single-electron transmission results.

Allows treatment of electron-reservoir couplings independent of electron energy.

Facilitates inclusion into correlated electron transport models.

Abstract

The electronic conductance of a molecule making contact to electrodes is determined by the coupling of discrete molecular states to the continuum electrode density of states. Interactions between bound states and continua can be modeled exactly by using the (energy-dependent) self-energy, or approximately by using a complex potential. We discuss the relation between the two approaches and give a prescription for using the self-energy to construct an energy-independent, non-local, complex potential. We apply our scheme to studying single-electron transmission in an atomic chain, obtaining excellent agreement with the exact result. Our approach allows us to treat electron-reservoir couplings independent of single electron energies, allowing for the definition of a one-body operator suitable for inclusion into correlated electron transport calculations.