Screening effects in a density functional theory based description of molecular junctions in the Coulomb blockade regime

TL;DR

This paper applies a DFT and NEGF-based method to study electrostatic screening effects on addition energies in benzene molecular junctions near aluminum surfaces, revealing significant energy reductions consistent with more complex approaches.

Contribution

It introduces a computationally efficient DFT-based approach to analyze screening effects in molecular junctions within the Coulomb blockade regime.

Findings

Addition energies are reduced by about a factor of two near surfaces.

The method's results align with those from more demanding quasi-particle calculations.

Screening effects significantly influence molecular junction energy characteristics.

Abstract

We recently introduced a method based on density functional theory (DFT) and non-equilibrium Green's function techniques (NEGF) for calculating the addition energies of single molecule nano-junctions in the Coulomb blockade (CB) regime. Here we apply this approach to benzene molecules lying parallel and at various distances from two aluminum fcc (111) surfaces, and discuss the distance dependence in our calculations in terms of electrostatic screening effects. The addition energies near the surface are reduced by about a factor of two, which is comparable to previously reported calculations employing a computationally far more demanding quasi-particle description.