Triple-domain effects on the electronic structure of Pb/Si(111)-( × ): Density-functional calculations

Electronic structure of the Pb/Si(111)-( 7 × 3 ) surface has been studied by using density-functional theory calculations for a representative structural model with a coverage of 1.2 ML. Our calculations do not reproduce all the bands reported in an angle-resolved photoemission spectroscopy (ARPES) study, but we find that this discrepancy could be resolved by taking into account the effect of the triple-domain structure of the ( 7 × 3 ) surface samples. We also find that, while the calculated Fermi surface for a single-domain ( 7 × 3 ) surface bears a ( 7 × 3 ) periodicity, the overlap of the Fermi surfaces for three different ( 7 × 3 ) domains reveals an effective (1 × 1) periodic pattern similar to the (1 × 1) Fermi surface measured for the ( 7 × 3 ) surface. Thus, the unusual (1 × 1) pattern appearing in the measured Fermi surface is not likely due to any strong (1 × 1) potential in the ( 7 × 3 ) surface as was speculated in the ARPES study.