Abstract
From an ab initio study, employing the plane-wave pseudopotential method and the density-functional scheme, we report on changes in atomic geometry, electronic states, and atomic orbitals for the clean and Bi-induced (2x4) reconstruction on the InP(001) surface. For the clean surface we have considered the well-accepted structural model characterized by an asymmetric In-P mixed dimer and a layer of threefold and fourfold In atoms. For the Bi adsorbed surface we have considered two different coverages: 0.5 and 0.25 monolayer (ML). For 0.5 ML coverage of Bi we considered two geometrical structures based on the alpha 2 and beta 2 models. Our calculations suggest that the alpha 2(2x4) model is more stable in the P-poor/Bi-rich condition. For 0.25 ML coverage of Bi, the ground-state structure forms the alpha 2 structure which is comprised of mixed Bi-P dimers in the top and third layers. These results are in agreement with the most recent core-level photoemission and scanning tunneling microscopy investigations. For both coverages the Bi/InP(001)-alpha 2(2x4) system is semiconducting, characterized with smaller band gap than the clean surface.