Investigations of intrinsic surface states have been generalized beyond the nearly free-electron model. Simple conditions for the existence of surface states have been derived, and these results are presented. Detailed calculations have been made for transition metals, in particular for copper, and reveal that a substantial density of surface states (i.e., ∼ 1 per surface atom) is a common occurrence.

• Received 9 July 1973

DOI:https://doi.org/10.1103/PhysRevLett.31.637