I love crystal field theory, but I would like to try and extend this idea to the f-orbitals. We know how the d-orbitals split in an a variety of environments, but how do the f orbitals split? I want to develop an assignment for my students where they can use their knowledge from the d-orbitals to think about how the f-orbitals would split. Any ideas? I know CFT is not as important for the lanthanides, but I think it could be an interesting extension to what students typically learn about CFT.