"Optimal" parameters were selected for the adaptive algorithms based on the tests described above. We selected a runtime constant of 0.0005 kcal 2 mol -2 ns -1 as this generally produced runs of sufficient length to match the non-adaptive 30 ns results. We retained our default of 5 replicate runs as this seemed to represent a reasonable compromise between fast equilibration and reliable detection of sampling issues, although we did not investigate this in detail. Because we did not use replica exchange and hence did not have to consider replica mixing, we spaced λ-windows with a large thermodynamic speed of 2 kcal mol -1 to accelerate equilibration. Finally, we retained the default equilibration detection parameters as these appeared to deliver robust performance.