Theoretical structure of a 1x1 reconstruction on the SrTiO3 (111) surface which density-functional calculations indicate is a low-energy structure for TiO2 rich surfaces. The surface contains 6-fold rings of edge and face sharing octahedral units, which leads to the stability of the structure; titanium prefers to be octahedrally co-ordinated.

Plot of the energies for the different valence compensated structures, versus stoichiometry with an 0.25eV error bar included, labeled with the relevant model; solid for TPSSh and empty for PBE. Also shown is the fracture surface energy (F), and the bulk termination (B), with the convex hull line shown in red.

The Small Unit Cell Reconstructions of SrTiO3 (111), Laurence D. Marks, Ann N. Chiaramonti, Fabien Tran and Peter Blaha, Surface Science, 603, 2179 (2009)