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Density-functional theory and plane wave basis are applied to calculate one-dimensional (1D) Au chains on the 1×2 missing row (mr) defected, and the added row (ar) reconstructed, TiO2 (110) surfaces. Single, dimer, and triple Au rows were considered. The single Au row binds strongly to the mr (2.83 eV) but much weaker to the ar surface (1.56 eV), with the Au-Ti bond lengths of 2.67 and 2.68 Å, respectively. For the Au dimer rows the most stable (2.51 eV) Au stripe is again more stable than the most stable dimer structure (2.06 eV) in the ar model. For triple Au rows on the mr surface the Au atoms form a stripe of v-form with the binding energy per atom of 2.42 eV, which is by 0.17 eV stronger than for the corresponding triple Au in the ar structure, the latter being suggested in the literature as the most favored structure of the clean surface. The charge redistribution in the Au atoms shows that the bonding between Au and surface atoms is determined by the electron transfer from the d-states to the more extended s-states. The charge density distribution and the increased density of occupied states around the Fermi edge suggest metallic behavior of the Au rows. Intra-chain and inter-chain spacings are determined by the substrate periodicity. The results strongly suggest that the surface has the missing row structure. The large inter-chain distance (13 Å) on the more or less insulating substrate makes this system ideal for studies of 1D phenomena and the catalytic behavior of Au on TiO2. Such 1D Au rows on the TiO2(110) surface have been produced experimentally [1,2].
[1] A. Locatelli, T. Pabisiak, A. Pavlovska, T. Mentes, L. Aballe, A. Kiejna, E. Bauer, J. Phys.: Condensed Matter 19, 082202, (2007), fast track communication.
[2] T. Mentes, A. Locatelli, A. Pavlovska, L. Aballe, E. Bauer, T. Pabisiak, A. Kiejna, submitted, (2007). |