@galihru/mnp

Integrated computational package for the single-nanoparticle electromagnetic response in the Rayleigh quasi-static limit. Composes dielectric-function evaluation with polarizability and optical cross-section computation into a unified, self-consistent simulation API.

Physical Scope

This package solves the single-nanoparticle optical response problem: given a metallic sphere of radius a << lambda embedded in a dielectric host medium, compute as functions of illumination wavelength:

1. Complex permittivity via the Drude free-electron model:

   

2. Complex polarizability via the Clausius-Mossotti relation:

   

3. Electromagnetic cross sections from the optical theorem:

   

Composed Packages

| Package | Description | |---|---| | @galihru/mnp-material | Drude dielectric model for Au, Ag, Al; constant epsilon; complex wave number | | @galihru/mnp-mie | Rayleigh polarizability; extinction, scattering, and absorption cross sections |

Install

npm install @galihru/mnp

API Reference

simulateSphereResponse(options) -- High-level

Computes the complete optical response of a metallic nanosphere in a single call.

import { simulateSphereResponse } from "@galihru/mnp";

const result = simulateSphereResponse({
  material:              "Au",   // "Au" | "Ag" | "Al"
  wavelengthNm:          548.1,  // nm -- scalar or Array for spectral scan
  radiusNm:              50,     // nm
  mediumRefractiveIndex: 1.33    // dimensionless refractive index of host medium
});

Return value:

| Field | Unit | Description | |---|---|---| | inputs | -- | Echo of all input parameters | | epsParticle | {re, im} | Complex permittivity of the metal particle | | epsMedium | {re, im} | Permittivity of the embedding medium | | alpha | {re, im} nm^3 | Quasi-static complex polarizability | | crossSection.cExt | nm^2 | Extinction cross section | | crossSection.cSca | nm^2 | Scattering cross section | | crossSection.cAbs | nm^2 | Absorption cross section |

Low-level Re-exports

All functions from sub-packages are re-exported directly:

import {
  // Dielectric models
  drudeEpsilon, makeDrudeMaterial, constantEpsilon, wavenumberInMedium,
  // Scattering
  rayleighPolarizability, rayleighCrossSections,
  // Complex arithmetic
  complex, add, sub, mul, div, sqrtComplex, fromReal,
  // Constants
  EV_TO_NM, HARTREE_EV
} from "@galihru/mnp";

Example -- Spectral Scan

import { drudeEpsilon, constantEpsilon, rayleighCrossSections } from "@galihru/mnp";

const wavelengths = [400, 450, 500, 548, 600, 700];

// Au permittivity across wavelengths
const epsAu  = drudeEpsilon("Au", wavelengths);

// Host medium: water (n = 1.33, eps = n^2)
const epsH2O = wavelengths.map(w => constantEpsilon(1.769, w));

// Cross sections for a 50 nm radius Au sphere
const spectra = rayleighCrossSections(wavelengths, 50, epsAu, epsH2O);

spectra.forEach((cs, i) =>
  console.log(
    wavelengths[i] + " nm  Cext=" + cs.cExt.toFixed(1) + " nm^2" +
    "  Cabs=" + cs.cAbs.toFixed(1) + " nm^2"
  )
);

Author

GALIH RIDHO UTOMO | [email protected] Universitas Negeri Semarang (UNNES) License: GPL-2.0-only