We note that the PGM approach is more computationally efficient than the Einstein crystal method (ECM), as it requires performing only two simulations of the physical end-states of interest vs. multiple simulations in perturbed Hamiltonians necessary for converging the ECM. The difference in cost can be quantified by comparing the amount of MD-generated samples used by the two methods. In this regard, PGM requires only ≈17% of the configurations needed by the ECM, leading to an increase in MD efficiency of factors between 5 and 6. Given that the FEs from PGMs in the current work have converged quite quickly during training, we anticipate that further efficiency gains can be reached in more complex molecular systems.