This shows that once Cu atoms are within ∼ 3 Å, the increase in stability caused by the formation of Cu bonds is stronger than Cu interaction with the monolayer. On WSe 2 and WTe 2 the distance between the single Cu atom and the two atom cluster for Offset-H has a minimum distance of 4.97 and 5.41 Å respectively, which is likely why a 3D structure does not form here.