Dipolar coupling of nanoparticle-molecule assemblies: An efficient approach for studying strong coupling

TL;DR

This paper introduces a computationally efficient dipolar subsystem approach to accurately predict strong light-matter interactions in nanoparticle-molecule assemblies, enabling analysis of larger systems beyond current methods.

Contribution

The study presents a novel dipolar coupling method that simplifies the calculation of optical spectra in nanoparticle-molecule systems, reducing computational demands while maintaining accuracy.

Findings

The subsystem approach accurately reproduces spectra compared to full quantum calculations.

The method effectively captures strong coupling effects in nanoparticle-molecule assemblies.

It can be extended to larger systems and include optical-cavity modes.

Abstract

Strong light-matter interactions facilitate not only emerging applications in quantum and non-linear optics but also modifications of materials properties. In particular the latter possibility has spurred the development of advanced theoretical techniques that can accurately capture both quantum optical and quantum chemical degrees of freedom. These methods are, however, computationally very demanding, which limits their application range. Here, we demonstrate that the optical spectra of nanoparticle-molecule assemblies, including strong coupling effects, can be predicted with good accuracy using a subsystem approach, in which the response functions of the different units are coupled only at the dipolar level. We demonstrate this approach by comparison with previous time-dependent density functional theory calculations for fully coupled systems of Al nanoparticles and benzene molecules. While the present study only considers few-particle systems, the approach can be readily extended to much larger systems and to include explicit optical-cavity modes.