CONICET | Buscador de Institutos y Recursos Humanos

In the present work, we propose an ionic Hamiltonian for describing the interaction of graphene with anadsorbed Co atom. In this approach, the electronic correlation effects, related to the many d orbitals involved inthe interaction, are taken into account by selecting appropriate electronic configurations of the adsorbed atom.The Hamiltonian parameters are calculated considering the localized and extended features of the atom-surfaceinteracting system. The physical quantities of interest are calculated by using a Green functions formalism,solved by means of the equations of motion method closed up to a second order in the atom-band coupling term.The charge and spin fluctuations in the adsorbed Co atom are inferred from density functional theory calculationsand assuming that the lower energy configurations obey Hund?s rules. The calculated spectral densities and theoccurrence probabilities of the different atomic configurations are analyzed as a function of the Co energy levelpositions and the surface temperature. In addition, the conductance spectra are calculated by using the Keldyshformalism and compared with existing measurements. We analyze the behavior, under variable bias and gatepotentials, of resonancelike features in the conductance spectra which can be related to transitions betweenatomic configurations of low occurrence probability.