Refractive index of C (Carbon, diamond, graphite, graphene, carbon nanotubes)

import lightsmith as ls

# C (Carbon, diamond, graphite, graphene, carbon nanotubes): Song et al. 2018: c-HOPG; n(e) 0.193–1.69 µm
c = ls.fetch_refractiveindex("main", "C", "Song-cHOPG-e", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(c.range_nm)  # (193, 1690) nm
eps = c.eps([633])  # complex permittivity

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_213873801eff/lightsmith"
c = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(c.source)  # citation and provenance travel with the data

# ... load c as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=c)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength