Stress-driven reconstruction of an oxide surface: the anatase TiO(2)(001)-(1 x 4) surface

The recently discovered (1 x 4) reconstruction of the stoichiometric anatase TiO(2)(001) surface is studied via first principles density functional calculations. We propose a new structural model for this reconstruction, which is energetically much more favorable than all the other available models, including the unreconstructed (1 x 1) surface. In this model, rows of TiO(3) species periodically replace rows of surface bridging oxygens of the (1 x 1) surface, thus leading to a relief of the large surface tensile stress present on that surface. The corresponding empty-state charge density distribution correctly describes the experimental scanning tunneling microscopy images.