Surface-embedded green function calculation using non-local pseudopotentials

We present a method for calculating the electronic structure of semi-infinite crystal surfaces using non-local norm-conserving pseudopotentials and the embedding approach of Inglesfield. The calculation consists of two major steps: (i) the energy-dependent embedding potential of a semi-infinite substrate is generated from the bulk crystalline potential, and (ii) a self-consistent surface Green function calculation is performed in the embedded surface region. In order to avoid overlapping with the ion-core region where the pseudopotential is non-local, the embedding surface S-c dividing the surface and substrate regions has a complicated curvy shape. Recently, Crampin et al. [J. Phys.: Condens. Matter 4 (1992) 1475] proposed a new method for generating the embedding potential acting on a plane surface that simulates embedding on the true embedding surface S-c. Our formulation refines upon their method in that there is no need to specify the actual shape of S-c in the whole calculational procedure. As an example, we calculate the electronic structure of the clean Al(111) and (root 3 x root 3)R30 degrees - K/Al(111) surfaces. (C) 1997 Elsevier Science B.V.