Effective Field Theory of Interacting \pi-Electrons

TL;DR

This paper introduces a cpi-EFT that models cpi-electron systems using three key parameters, enabling analysis of molecular screening, electronic spectra, and van der Waals interactions in molecular junctions.

Contribution

The paper develops a novel cpi-EFT framework with three effective parameters, providing new insights into screening, conductance spectra, and dispersion forces in molecular electronics.

Findings

Model of screening in molecular junctions using image multipole moments.

Calculation of HOMO-LUMO gap reduction in benzene.

Analysis of cpi-electron contributions to van der Waals interactions.

Abstract

We develop a \pi-electron effective field theory (\pi-EFT) wherein the two-body Hamiltonian for a \pi-electron system is expressed in terms of three effective parameters: the \pi-orbital quadrupole moment, the on-site repulsion, and a dielectric constant. As a first application of this \pi-EFT, we develop a model of screening in molecular junctions based on image multipole moments, and use this to investigate the reduction of the HOMO-LUMO gap of benzene. Beyond this, we also use \pi-EFT to calculate the differential conductance spectrum of the prototypical benzenedithiol-Au single-molecule junction and the \pi-electron contribution to the van der Waals interaction between benzene and a metallic electrode.