Fig. 2.

(A) The simulated free energy profiles, $\beta \mathrm{\Delta }G\left(N;d\right)$, as a function of the number of water molecules between the surfaces, N, display marked kinks (highlighted by circles). Here, $\beta =1/k_{\text{B}}T$, with $k_{\text{B}}$ being the Boltzmann constant and T being the temperature. The size of the largest error bar is also shown for $d=23$ Å and $N=400$. (B) The kinks are also apparent in the smoothed derivatives of the free energy profiles, which display a sharp decrease in the vicinity of $N_{\text{kink}}$.