We conduct a theoretical examination of the electronic and magnetic
characteristics of end-modified 7-atom wide armchair graphene nanoribbons
(AGNRs). Our investigation is performed within the framework of a single-band
Hubbard model, beyond a mean-field approximation. First, we carry out a
comprehensive comparison of various approaches for accommodating
di-hydrogenation configurations at the AGNR ends. We demonstrate that the
application of an on-site potential to the modified carbon atom, coupled with
the addition of an electron, replicates phenomena such as the experimentally
observed reduction in the bulk-states (BS) gap. These results for the density
of states (DOS) and electronic densities align closely with those obtained
through a method explicitly designed to account for the orbital properties of
hydrogen atoms. Furthermore, our study enables a clear differentiation between
mean-field (MF) magnetic moments, which are spatially confined to the same
sites as the topological end-states (ES), and correlation-induced magnetic
moments, which exhibit localization along all edges of the AGNRs. Notably, we
find the robustness of these correlation-induced magnetic moments relative to
end modifications, within the scope of the method we employ