Hello, I am doing some calculations of the band structures of the surfaces of several materials. I would like to perform passivisation on these surfaces so as to remove any metallic surface states. Unfortunately, I was never great at chemistry and so it's not obvious to me how to choose what atoms or molecules to use to passivate the surface (ideally as few as possible to reduce computation time). I've been looking for a reference that talks about how one might do so, ideally with some examples that are not just the simplest possible case. Anyone know of a good reference? To be clear, when I say passivate here what I mean is that I want to pair any unpaired electrons at the surface that result from "cutting" the bulk to form the surface by bonding them with another atom in such a way that there is a band gap at the surface. Thanks.