Figure 15.

Left: An illustration of the model channel. The “bulk” MM water molecules are shown in blue, while the QM water molecules are colored by atom type. The eight dipoles are shown in green. For the channel of radius 3.5 (5.0) Å, the (inner region) box edge-length along X and Y is 17.2 (20.4) Å. Each dipole is comprised of charges of +0.5e (+0.6e) and −0.5e (−0.6e) separated by 1.5 Å for the narrower (wider) channel, with the positive end pointing toward the channel. Top right: Proton transfer free energy profiles along ζ (two MM oxygen atoms fixed at (0, 0, 10) and (0, 0, −10) are used as the donor and acceptor for defining ζ. Bottom right: RDF of water O atoms about the “hydronium” O when it is near the center of the channel along z. The number after “|” in the legend results from integration of the first peak of the RDF.