This second part of the tutorial consists in a set of guided exercises that exemplify how to make basic additions to the code, taking as starting point the template-like, relatively self-contained submodule Hamiltonian_Hubbard_Plain_Vanilla_smod.F90, which is also a good display of ALF’s internal workings.
These worked-out exercises, together with ALF’s modularity, boosted by its Predefined Structures, should make getting your hands dirty less daunting than it may sound.