Fig. 4.

Water dipole orientation inside the SWNT. (A) Distributions of the averaged dipole orientation of water molecules inside the SWNT, θ, for various distances δ. The distribution has two peaks at about cos 〈θ〉 = ±0.85 for δ = 1 Å and a single peak at cos 〈θ〉 = 0 for δ = 0.5 Å. (B) Profile of 〈cos ϕ〉 along the SWNT channel. (C) Examples of the average values of ϕ, denoted by 〈ϕ〉, in three different regions for δ = 1, 0.75, and 0.5 Å: central-region (black), other regions for positive and negative z values (green and red). (D) Probability of bipolar orientation of all water molecules inside the channel. The red line is a linear fit for probability = −1.91 × (δ − 1.0).