Fig. 7.

Comparison of per-charge change in salt ion association for duplex melting transition from all-atom and cylindrical models. All-atom (Fig. 6, symbols) and cylindrical model (Table 2, circles) predictions are plotted as a function of duplex charge. Calculations of $\Delta n_{\mathrm{u}}^{\text{coul}}$ for cylindrical model of ds and ss DNA are performed with radii a_ds = 9.4 Å, a_ss = 7 Å, and charge separations b_ds = 1.7 Å, b_ss = 3.4 Å.⁹