Average hydration number for permeating ions along the channel axis.

<p>(A) Na<sup>+</sup>; (B) K<sup>+</sup>. The hydration number was calculated by determining the number of water molecules within a certain cutoff distance of the permeating ion. The cutoff used was 2.8 Å for Na<sup>+</sup> and 3.2 Å for K<sup>+</sup>. The hydration number values shown here have been averaged over the trajectory for the respective window. Error bars are shown in pink.</p>