États de surface du sodium dans l'approximation des électrons quasi-libres

Electron states located near a (110) surface of a Na crystal are investigated by the method of matching the crystal wave function to the outside solution at the surface. The lower energetic states are in the fundamental state. An “anormal” optical band situated about 1.8 eV is discussed when the imaginary part of the dielectric function ?₂ has been determinated considering transitions with the k-vector component parallel to the surface.