Excitons at the (001) surface of anatase: Spatial behavior and optical signatures

Within an ab initio study, based on the application of Many-Body Perturbation Theory approaches on top of ground-state Density Functional Theory calculations, we study the optical behavior of the TiO(2) anatase (001) surface. We focus on the (1 x 1) and the (1 x 4) reconstructions, both experimentally observed, which reveal a different optical response and an anisotropy, in the (001) plane, not present in the bulk phase. The determination of the spatial behavior of the electron-hole photoexcited couple provides a possible explanation of the observed enhanced photocatalytic activity of TiO(2) anatase nanostructures with a high percentage of (001)-(1 x 1) exposed facets.