Image states on beryllium surfaces with low indices

Abstract

Using the self-consistent pseudopotential method, we have calculated the binding energy of the image states for the (0001) \((10\bar 10)\), and \((11\bar 20)\) surfaces of beryllium. It is shown for the (0001) face that there exists a pronounced resonance image state with n=1 and energy −0.95 eV at the point \(\bar \Gamma \) of the surface Brillouin zone. In the \((10\bar 10)\) surface, which has a wide band gap in the vicinity of the vacuum level, the calculated image state with n=1 at the point \(\bar \Gamma \) has energy −1.2 eV and is a surface state of gap type. For the \((11\bar 20)\) face in the vicinity of the point \(\bar \Gamma \) band gaps are absent. However, the symmetry of the bulk states near the vacuum level enables the existence of a resonance image state with n=1 and energy −0.6 eV.