First Principles Quantum Transport with Electron-vibration Interactions: A Maximally Localized Wannier Function Approach

TL;DR

This paper develops an ab initio inelastic quantum transport method using maximally localized Wannier functions, combining density-functional theory and Green's functions to study electron-vibration interactions in molecular junctions.

Contribution

It introduces a novel formalism that integrates Wannier functions with inelastic transport calculations, enabling detailed analysis of vibrational effects in quantum conductance.

Findings

Observed conductance steps related to vibrational modes.

Demonstrated the method on benzene junctions and carbon nanotubes.

Analyzed non-equilibrium vibrational populations driven by current.

Abstract

We present an ab initio inelastic quantum transport approach based on maximally localized Wannier functions. Electronic-structure properties are calculated with density-functional theory in a planewave basis, and electron-vibration coupling strengths and vibrational properties are determined with density-functional perturbation theory. Vibration-induced inelastic transport properties are calculated with non-equilibrium Green's function techniques, which are based on localized orbitals. For this purpose we construct maximally localized Wannier functions. Our formalism is applied to investigate inelastic transport in a benzene molecular junction connected to mono-atomic carbon chains. In this benchmark system the electron-vibration self-energy is calculated either in the self-consistent Born approximation or by lowest-order perturbation theory. It is observed that upward and downward conductance steps occur, which can be understood using multi-eigenchannel scattering theory and symmetry conditions. In a second example where the mono-atomic carbon chain electrode is replaced by a (3; 3) carbon nanotube, we focus on the non-equilibrium vibration populations driven by the conducting electrons using a semi-classical rate equation.