Preferred binding sites of Cs ⁺ within the SF. (A–C) Conduction trajectory for Cs⁺ along SF axis from simulations in mixed-ionic solutions with K⁺, at different voltages and for different initial cation placements within the SF: Cs⁺ is preplaced in p23 and K⁺ in p34 at simulations with an applied voltage of (A) −150 mV, (B) −500 mV, and (C) −700 mV. (D–F) The conduction pattern of Cs⁺ and K⁺ is depicted in D for a simulation at −500 mV, with the initial placement of K⁺ proximate to p23 and of Cs⁺ proximate to p34. Snapshots of trajectory frames at timepoints indicated by arrowhead markers in D are shown in subplots (E and F).