We also confirm this behaviour with the effect of van der Waals interaction included for the exfoliation energy calculations for both n-type and p-type materials (images b and d in Figure ). The effect of the vdW corrections serves to raise the exfoliation energy values higher than those obtained using the PBE functional, which is to be expected given that the instantaneous dipoles create forces of attraction and therefor make materials harder to pull apart. The nature of the relationship between exfoliation energy and effective mass standard deviation remains unchanged at this higher level of theory. This is a fortuitous result as it benefits the community to be able to screen for 2D materials at as rapid a level of theory as possible. However, we note that when the van der Waals interaction is not considered, there are several materials that show negative values for the exfoliation energy (see Figure in the SI for the specific cases). This should not be possible, as negative exfoliation energies imply that the structure of the material is unstable prior to layer separation, even though we screened for only thermodynamically stable materials. The expected positive respectively. Information about all these materials can be found in Table .