FIG. 4.

Na⁺–Cl⁻ ion pair PMF W(d) [Eq. (10)] calculated using the GB approach with the analytical estimation of the “Sphere” [Eq. (6)] and “Neck” [Eq. (7)] integrals and the new dielectric boundary (DB) definition (see Fig. 3) (black solid line), numerical solution of PB equation with the “standard” solvent excluded surface (SES) based definition of the DB and water probe radius $r_w$ = 1.4 Å (solid red line), and the results from the MD simulations with explicit TIP3P (stars)⁹⁹ and SPC/E (diamonds)¹⁰⁰ water models.