Energetically accessible reconstructions along interstitial rows on the rutile (110) surface

First principles calculations of a selected reconstruction on the stoichiom etric (110) surface of rutile TiO2 are reported. 2-8 layer (1x2) slabs with reconstructed patterns on one or both faces are computed, allowing direct comparison of energies. The reconstruction features [001] rows of tetrahedr ally-coordinated Ti cations in vertically-oriented interstices. A completel y reconstructed (1x1) surface is just 0.03 +/-0.02 J m(-2) less stable than the usual (1x1) bulk termination and may be the corrugated (1x1) surface o bserved during oxidative growth at 700-1000 K. Isolated interstitial rows a re also predicted to occur, at a similar energetic cost (0.1 +/-0.1 eV per TiO2).