How to choose specified clusters besides of the cutoff radius?

[sjtuzhanglei]

Dear CASM developers,

I am wondering that a brute-force way of generating and fitting a set of clusters within a given cutoff radius might not be good for a 2D cluster expansion, where I only care about the interactions between adsorbates.

Is there a way to exclude clusters that contain atoms of the substrate?

Do you think this selection of clusters will be helpful in terms of physical interpretation and fitting robustness?

Thanks, Lei