Extended Data Fig. 8: FDTD simulations of differently modified 432 helicoid III nanoparticles to identify design guidelines.

a, Calculated g-factors of chiral nanoparticles corresponding to models using parameterized chiral nanoparticles (samples 1–19). The different samples represent chiral nanoparticles with: 1–3, edge lengths L of 100–200 nm; 4–7, gap widths w of 10–40 nm; 8–15, gap depths d of 30–100 nm; or 16–19, gap angles t of 30°–75°. The default parameters are L = 150 nm, w = 20 nm, d = 70 nm and t = 60°. b, Calculated absorbance and CD of chiral nanoparticle samples 7 (L = 150 nm, w = 40 nm, d = 70 nm, t = 60°), 12 (L = 150, w = 20, d = 70, t = 60) and 14 (L = 150, w = 20, d = 90, t = 60), using N = 10¹⁵ m⁻³ and l = 10⁻³ m (i and ii). The calculated electric-field intensity of each of these samples on the illuminated face (z = −75 nm) at RCP illumination at the first CD peak—of 600 nm, 670 nm and 720 nm, respectively—is also shown (iii–v). c, Calculated g-factors of chiral nanoparticles corresponding to models 20–32, using chiral nanoparticles with various geometry changes: 20–22, chiral nanoparticles with increasing curvature; 23–26, chiral nanoparticles with aspect ratios of 1–3; 27–31, chiral nanoparticles with hollow structures constructed by removing cubic domains with side lengths of 70–130 nm; and 32, planar-triangle-based chiral nanoparticle with an edge length of 150 nm. The default size of chiral nanoparticles 20–31 is 150 nm.