Same self-consistent discrete-dipole (coupled-dipole) model as the 3D version — N Lorentzian gold-plasmon oscillators driven by circularly-polarized light and coupled through their near-field radiation — but here it is read out as a helical-wheel phasor map instead of a 3D render, the classic 2D-native way structural biologists and photonics papers unroll a helix: angle = azimuthal position φᵢ around the helix axis, radius = turn index (each successive turn spirals one ring further out, so turns never overlap). This is not a camera projection of the 3D scene — the physical helix radius is constant; the plot's radius axis is repurposed to encode "which turn", something no single 3D viewing angle can show at once.
α(λ) = α₀ / [(1 − x²) − iΓx], x = λ₀/λ
E_inc,i = E₀(x̂ ± iŷ) e^(ikzᵢ) (LCP: +, RCP: −)
p_i = α(λ)[E_inc,i + Σ_j≠i κ₀(a/R_ij)³ (3n̂(n̂·p_j) − p_j) e^(ikR_ij)]
σ_ext(λ) ∝ Σ_i Im[E_inc,i* · p_i] (optical theorem)
CD(λ) = A_LCP(λ) − A_RCP(λ), g = 2·CD / (A_LCP + A_RCP)
- Each dot on the wheel is one nanoparticle; its brightness encodes induced-dipole magnitude |pᵢ| and the short radial tick encodes the dipole's complex phase, exactly as solved from the 3D near-field-coupled equations (all distances R_ij are still true 3D distances — the physics is identical, only the readout is 2D-native).
- Handedness flips the sign of the azimuthal step between particles — flip it and every phasor's phase pattern mirrors, and CD flips sign.
- N / pitch control the geometric winding that sets near-field coupling strength; λ sweeps the driving wavelength across the plasmon resonance.
- The spectrum panel plots CD(λ) from 450–700 nm, recomputed from the same solver.