I'm going through some things to prep my AtomsBase introductory materials for the MolSSI workshop and noticed that at the moment, DFTK provides functions to convert to prototype interface implementations, but why not just (also, or instead) have Model directly implement the interface and subtype AbstractSystem? I could see some advantages down the line where if you had to pass information back and forth quite often, you wouldn't want to repeatedly incur the computational cost of conversion.

It's certainly not a blocker for any particular thing I'm doing right now, but figured I'd start the conversation as it doesn't seem it would be too difficult to do. I'd be happy to draft a PR if this makes sense!