The ABF algorithm was applied to each window until convergence was reached. As for other importance sampling techniques, the assessment of convergence is not trivial. Several necessary conditions for convergence were monitored to determine a reasonable trade-off between computational cost and precision. These included the uniform increase of the samples across bins, the absence of further changes to the PMF, and the continuity of the mean force between different windows (see the Supporting Information). The mean force converged more slowly in the windows that were close to the surface due to the existence of several orientations and conformations that correspond to different values of the mean force. The total simulation times required to obtain converged PMFs varied between 165 ns and 750 ns for windows adjacent to the surface and between 75 ns and 150 ns for the others. The calculations using n-hexadecane converged more quickly than those with PAO4. This is consistent with the observations of Jaishankar et al., who found that calculations converged more quickly for n-heptane than n-hexadecane, due to shorter relaxation times of the former.