First-Principles Investigations of the Atomic and Electronic Structure of Pb, Sn and Ge Adsorbed on the ${\rm Ge}(111)\mbox{-}(\sqrt{3}\times\sqrt{3})$ Surface

Abstract

Submonolayer adsorption of group-IV elements (Ge, Sn, Pb) on the Ge(111) surface has been investigated using first-principles pseudopotential total-energy and force calculations. The most prominent adsorption geometries, namely T4 and H3, are compared with respect to their atomic and electronic structure. As the most striking result, our calculations favor adsorption of adatoms in thresfold-symmetric T4 sites for all three different adatom species in agreement with earlier predictions and experiment.

Fermi surface and electronic structure of Pb/Ge(111)

“…The dispersion of S 2 agrees also well with other density-functional theory calculations for this surface. 22 We conclude that the electronic band structure of the ␣Ϫͱ3 phase is well explained within one-electron theories. These results agree well with previous experimental evidence, 28 but disagree with more recent results, 21 where no dispersing surface bands were found.…”

“…28,32 The lower surface band S 1 at ϳ1 eV binding energy ͑BE͒ ͓see are dispersing, indicating long-range order in the surface, and a significant degree of delocalization in the valence electrons. 12,22,32,33 A simple electron counting shows that the number of valence electrons in the ␣Ϫͱ3 unit cell ͑7͒ is odd. Thus, S 2 is half-filled and the surface should be metallic.…”

“…This is an important requirement in the model exposed above for the transition, and is also expected from theoretical calculations. 12,22 In fact, the metallic character of the ␣Ϫͱ3 phase is due to the existence of a halffilled surface-state band 12 ͑see also below͒. In an effort to understand the nature of both RT and LT phases, we have analyzed the electronic band structure of both phases.…”

Electronic structure of Sn/Si(111)-(3×3)R30°Lobo1, Tejeda2, Mugarza3 et al. 2003Phys. Rev. B193200View full textAdd to dashboardCite

“…4. 36 Besides the existence of the split component, another significant difference between the experimental data and the prediction for a flat ͱ3 phase is the detection of surface-state intensity at the ⌫ point ͑normal emission͒. Note that the ͱ3 surface state lies above the Fermi energy at ⌫ .…”

Temperature-dependent gaps in the half-filled Hubbard model on a triangular lattice

“…15͒ show a clear insulating behavior with a large gap and no phase transitions. These systems have been studied theoretically both within the local-density 5,16,17 ͑LDA͒ and the Hartree-Fock 18,19 approximations. Quite recently 20 the LDAϩU approach has been used to include strong on-site repulsions in SiC͑0001͒.…”