Worm-Like Chain Model

The worm-like chain (WLC) model describes semiflexible polymers like DNA, actin, and collagen. The persistence length L_p = κ/(k_BT) quantifies bending rigidity: for L ≫ L_p the chain is flexible; for L ≪ L_p it is rod-like. The tangent correlation decays as ⟨t(s)·t(0)⟩ = e^−s/L_p. End-to-end distance: ⟨R²⟩ = 2L_pL[1 − L_p/L(1−e^−L/L_p)].