Madelung Formalism for Electron Spill-Out in Nonlocal Nanoplasmonics

Area of Science:

• Plasmonics
• Quantum mechanics
• Computational physics

Background:

• Modeling multiscale plasmonic systems is challenging.
• Classical theories lack quantum effects, while quantum electrodynamics is computationally intensive.
• Existing models struggle to incorporate quantum effects like electron spill-out and nonlocality.

Purpose of the Study:

• To develop a practical model for multiscale plasmonic systems.
• To incorporate quantum effects, specifically electron spill-out, into hydrodynamic models.
• To validate the proposed model against established numerical methods.

Main Methods:

• Utilizing the Madelung form of the hydrodynamic Drude model.
• Describing the metal-dielectric interface with a super-Gaussian function to include electron spill-out.
• Performing calculations for a two-dimensional nanoplasmonic wedge.

Main Results:

• The proposed model shows good qualitative agreement with nonlocal full-wave numerical calculations.
• The results validate the incorporation of electron spill-out using the super-Gaussian function.
• A conformal transformation perspective is offered for qualitative explanation.

Conclusions:

• The Madelung form of the hydrodynamic Drude model offers a viable approach for multiscale plasmonics.
• This methodology allows for the modular inclusion of quantum effects.
• The approach can be extended to incorporate other quantum phenomena in plasmonic systems.