Ab-initio approach for gap plasmonics

TL;DR

This paper introduces a first-principles methodology to compute tunnel conductivities in gap plasmonics, revealing complex frequency-dependent behaviors that enhance understanding of charge transfer in nanoscale metallic gaps.

Contribution

It develops a density functional theory-based approach to calculate tunnel conductivities, advancing the modeling of quantum effects in gap plasmonics beyond previous simplified models.

Findings

Frequency dependence of tunnel conductivity is more complex than previously assumed.

First-principles calculations show significant variation in tunnel conductivities at infrared and optical frequencies.

Methodology applied to a sodium jellium model demonstrates its effectiveness in realistic scenarios.

Abstract

Gap plasmonics deals with the properties of surface plasmons in the narrow region between two metallic nanoparticles forming the gap. For sub-nanometer gap distances electrons can tunnel between the nanoparticles leading to the emergence of novel charge transfer plasmons. These are conveniently described within the quantum corrected model by introducing an artificial material with a tunnel conductivity inside the gap region. Here we develop a methodology for computing such tunnel conductivities within the first-principles framework of density functional theory, and apply our approach to a jellium model representative for sodium. We show that the frequency dependence of the tunnel conductivity at infrared and optical frequencies can be significantly more complicated than previously thought.