Quantized Plasmon Modes for Metallic Nanoparticles of Arbitrary Shape with a Generic Dielectric Function

In this work, we introduce an effective approach to quantize the electromagnetic response of plasmonic metallic nanostructures. Their shape is arbitrary, and they feature a realistic description of the frequency-dependent metal dielectric function that is based on experimental data. The derived quantum modes correctly reproduce the linear response macroscopic polarization of the nanoparticle upon external drive according to classical Maxwell's equations in the quasistatic limit. We further investigated the coupling of these modes to a quantum-chemical molecular description. The presented methodology paves the way for accurate modeling of a plexcitonic system, where strong plasmon-molecule coupling and/or strong-driving fields call for a quantized description of the plasmonic response.