To create the slab structures for high-throughput ab initio calculations, we developed a python code with the help of the pymatgen toolkit to expand the relaxed crystal cell along the axis in which the effective mass has its largest value, so that the unit cell length is not less than 15 angstroms. Then, the code adds a fake atom incrementally throughout the lattice space and collects the distance from that atom to its closest other atom (so-called nearest neighbour distance). After doing this 1,600 times across the unit cell, the code reports back the position of the fake atom that gives the maximum nearest neighbour distance. Once the coordinates of fake atom have been determined, the code will pull the crystallographic cell apart by 10 angstroms (to ensure that the periodic boundaries of the cell don't allow the surfaces to interact with themselves) along the high-effective mass axis. A summary of this process and example slab construct can be seen in Figure . Please do not adjust margins Please do not adjust margins All of these slabs were subject to static calculations to obtain internal energy without ionic relaxation at the PBE or PBE+vdW level of theory. The exfoliation energy could then be obtained by the formula: