SYMMETRY OF SURFACE-STATES

The symmetry of surface states on metal surfaces is investigated by gr oup-theoretical methods. The surface states are represented in the lin ear-combination-of-atomic-orbitals approximation. This approach yields a qualitative characterization of surface states with respect to thei r orbital composition, charge distribution, position of nodal planes, etc., simply on the basis of existing bulk-band-structure calculations . Symmetry selection rules are easily derived and examples are given, where erroneous assignments and ambiguities in the literature could be clarified by the present method.