The field-induced states at the surfaces of the nearly-free-electron metals

We have studied theoretically the energy spectra of the field-induced electronic states, generated by the positive external electric field applied to the Au(001) and Au(111) surfaces. The aim of this paper was to investigate the influence of the Schockley-inverted energy gap in the metal band structure on the energies of these states. The investigations have been performed for different intensitiesF of the applied electric field (0<F}<10⁸ V/cm). Our results indicate that the crystal potential influences considerably the energy spectra of the field-induced states. This effect is especially important in the case where these states appear near the energy gap.