In several papers and contexts I've seen this phrases like this used:
The nitrogen-vacancy in diamond is an atom-like system in the solid state.
What does "atom like system" mean exactly? I've done a google search and turned up little. It seems to be a field specific term. My guess is that the system of (for example) a nitrogen and vacancy pair can be modeled together using standard atomic model (like the standard hydrogen atom system that's studied in QM).
An explanation of what it specifically means, i.e. what assumptions you can make about the system that defines it as "atom like" would be appreciated.