Charge-transfer mechanism for the (monolayer graphite) /Ni(111) system

The electronic states of a monolayer of graphite on a Ni(111) substrate are investigated with use of first-principles self-consistent calculations. A notable feature of this system is that a formerly empty ${\mathrm{\pi }}^{\mathrm{*}}$ orbital of the graphite overlayer is now occupied because of its interaction with the occupied orbitals of the nickel substrate. Because there is a substantial spatial overlap between the wave functions of the substrate and overlayer orbitals, and because their energy difference is small, a charge transfer into the overlayer ${\mathrm{\pi }}^{\mathrm{*}}$ orbital occurs.