We were able to have sufficiently converged simulations with ∼10-20 ns of MD/NCMC simulations, which is computationally equivalent to 44-88 ns of MD simulations. Thus, the computational cost of MD/NCMC simulations is in the same order of magnitude of that for AFE calculations. Note that for n binding modes, we have to perform n -1 AFE calculations to obtain the population distribution, whereas for MD/NCMC we just need to perform a single simulation.