arXiv subjects

Christos Mystilidis

Publications and source records attributed to Christos Mystilidis.

6 recordsLinked to original sources

arXiv2026

OpenMUSTANC (MUltiple Scattering Theory At Nanoplasmonic Cavities): A MATLAB toolbox for the simulation of Plasmonic Sphere Aggregates

Mesoscopic physical models, including the Hydrodynamic Drude Model (HDM), the Generalized Nonlocal Optical Response (GNOR) Model, and the Surface Response Model (SRM), have been proposed to investigate nonlocal effects in nanometric structures. The combination of classical electromagnetism with these mesoscopic material models calls for new computational electromagnetic (CEM) algorithms, or update of conventional ones, in what is termed computational mesoscopic electromagnetics (CMEM). In this work, we present a MATLAB toolbox for the simulation of multiple spherical interfaces with arbitrary relative positions, with the incorporation of the aforementioned mesoscopic models. The method exploits vector spherical wave functions to properly express electric and magnetic fields, an S matrix formulation for the efficient treatment of incident and scattered fields at spherical interfaces, and a translation matrix to deal with propagating waves with different expansion centers. Excitation sources can be chosen among arbitrarily polarized plane waves, dipoles and electron beams. For the post-processing part, the calculation of cross sections and far/near-field mapping; fluorescence enhancement, Purcell factor and quantum yield; and cathodoluminescence and electron energy-loss probability is implemented. The toolbox is built in a modular manner, and each part (routine) has its own important functionality. This paper provides a full explanation of the proposed highly efficient and general toolbox, and a detailed guideline for researchers in the nanoplasmonics community.

physics.comp-ph↗

arXiv2026

Gibbs Phenomenon and Friedel Oscilations: Similarities, Differences, and the Educational Potential of their Comparison

We explore the similarities and differences between the Gibbs phenomenon in partial Fourier representations of discontinuous signals and Friedel oscillations in the electron density of a solid near an anomaly. Inspired by the apparent similarities of the two phenomena, we perform a detailed exploration of both from the viewpoint of an engineer being introduced to a concept from solid-state physics. Focusing on the density of an one-dimensional electronic gas confined by a square potential, we show that, despite the similarities, Friedel oscillations cannot be attributed to the inability of a partial Fourier series to describe a discontinuity. Nevertheless, the two phenomena do exhibit similarities, which can be exploited to develop intuition. By adopting an educational style, we hope to establish some common language between electrical engineers and condensed-matter physicists, hoping that this can further inspire the two communities to seek intuition and further comprehension within neighbouring but different disciplines.

cond-mat.other↗

arXiv2025

Overcoming Computational Bottlenecks in Quantum Hydrodynamics: A Volume-Based Integral Formalism

Mesoscopic models of the optical response of metals have emerged as fundamental building blocks in quantum plasmonics, in principle overcoming the computational bottlenecks of ab initio techniques by implementing aspects of the atomistic description of the metal in otherwise classical calculations. Nonetheless, even these approaches are eventually hindered by demanding computations due to sophisticated material response. Here, this issue is addressed for the advanced Self-Consistent Hydrodynamic Drude Model (SC-HDM), which captures both nonlocal electron dynamics and electron spill-out, through a Volume Integral Equation (VIE) method. Adopting an IE-based method shifts perspective from the commonly employed Differential Equation (DE)-based ones, demonstrating significant computational efficiency. The VIE approach is a valuable methodological scaffold: It addresses SC-HDM and simpler models, but can also be adapted to more advanced ones. For spherical nanoparticles (NPs), using the inherent symmetries, similar performance for three increasingly complicated material models is achieved, breaking the taboo that increased sophistication in material response requires taxing simulations. Mesoscopic material-response functions can be readily extracted from the VIE implementation, thus circumventing the need for lengthy microscopic calculations. This method opens a new way of modeling quantum hydrodynamic NPs and will serve as essential benchmarking tool for recipes addressing more complicated geometries.

physics.comp-ph↗

arXiv2025

An S-matrix Formalism for the Nonclassical Optical Response of Plasmonic Sphere Aggregates

A computational method for the scattering of light by multiple nonclassical plasmonic nanospheres, each of which has multiple (non-)concentric dielectric or metallic layers, is presented. The electromagnetic (EM) response of the free electrons in the metals is described by three popular mesoscopic models: the nonlocal hydrodynamic Drude model (NLHDM) and its diffusive variant, namely the generalized nonlocal optical response (GNOR) model, as well as the surface response model (SRM). The main equation behind the method is set up by detailing the evaluation of the S-matrix for each individual spherical interface and the interactions amongst the interfaces. The algorithm is numerically validated by comparing with an in-house boundary element method (BEM) solver for a spherical NP with two smaller embedded spheres, and physically checked on a trimer configuration, where the responses from the NLHDM and SRM are contrasted with the local response model (LRM). In both cases a very good agreement is seen regarding frequency shifts and field enhancements.

physics.comp-ph↗

arXiv2023

The Uniqueness Theorem for Nonlocal Hydrodynamic Media

We investigate a fundamental electromagnetic theorem, namely the uniqueness theorem, in the context of nonlocal electromagnetics, as simulated by a popular semiclassical model, the Hydrodynamic Drude Model (HDM) and extensions thereof such as the Generalized Nonlocal Optical Response (GNOR). The derivations and proofs presented here give a theoretical foundation to the use of the Additional Boundary Conditions (ABCs), whose necessity is recognized and underlined in virtually all implementations and applications of HDM. Our proofs follow a mathematically relaxed style, borrowing from the literature of established electromagnetics textbooks that study the matter from an engineering perspective. Through this simpler route we deduce clear and intuitive material-response requirements for uniqueness to hold, while using a familiar parlance in a topic that is mostly studied through a physics perspective. Two numerical examples that examine the problem from either a semianalytical or a purely numerical viewpoint support our findings.

physics.app-ph↗

arXiv2020

On the Application of Numerical Methods to Hallen's Equation: The Case of a Lossy Medium

A previous paper analyzed in detail the difficulties associated with the application of numerical methods to Hallen's integral equation with the approximate kernel for the case of a lossless surrounding medium. The present paper extends to the case where the medium is conducting and points out similarities and differences between the two cases. Our main device is an analytical/asymptotic study of the antenna of infinite length.

physics.comp-ph↗