Refractive index of AuAl₂ (Gold-aluminium intermetallic, Purple plague)

import lightsmith as ls

# AuAl2 (Gold-aluminium intermetallic, Purple plague): Chen and Lynch 1988: n,k 0.22–0.79 µm
aual2 = ls.fetch_refractiveindex("other", "AuAl2", "Chen", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(aual2.range_nm)  # (220, 790) nm
eps = aual2.eps([633])  # complex permittivity

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_c95e68777f89/lightsmith"
aual2 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(aual2.source)  # citation and provenance travel with the data

# ... load aual2 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=aual2)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=790, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength