Surface states and dipoles on Si(111)1×1:Na

A theoretical study of the interface formed by adsorption of one monolayer of Na on the Si(111) surface is presented. The equilibrium structure is predicted by minimizing the energy using the first principles pseudopotential method and local density approximation. The dispersion of the Na induced surface states, and the dipole resulting from charge transfer from the Na 3s orbitals into these surface states is calculated. The ionization potential of the overlayer system is predicted to be 2.1 eV.