A density functional theory study of atomic steps on stoichiometric rutile TiO2(110)

We present a detailed theoretical study of the energetics of stoichiometric steps on the (110) surface of rutile TiO2. Step structures running along the 〈001〉, 〈11¯1〉, and 〈11¯0〉 directions including bulk-terminations and possible reconstructions have been considered. A robust method for extracting surface and step energies of vicinal surfaces, where the surface energies converge slowly with respect to slab thickness, is outlined and used. Based on the calculated step energies a 2D Wulff-construction is presented from which it can be concluded that in equilibrium only oxygen terminated steps running along the 〈001〉 directions and reconstructed steps along the 〈11¯1〉 directions should be present. Finally it is found that under conditions of stoichiometry the reconstructed 〈11¯1〉 steps should be more than twice as abundant as oxygen terminated 〈001〉 steps