There is another way proposed by Artrith and Behler 138 to explore the poorly sampled regions of the configuration space. This approach is based on the limited extrapolation capabilities of NN PES: if some regions were not covered well, different NN potentials would give different energy predictions for configurations in these regions. Namely, these regions are of high uncertainty. Interestingly, this sampling method is self-driven to explore configuration space without the dynamic simulations. Besides, they introduce an energy-dependent weighting function to avoid adding some highly distorted configurations, which may significantly decrease the fitting accuracy. Practically, the following steps need be considered for sampling: