Review of Systematic Tendencies in (001), (011) and (111) Surfaces Using B3PW as Well as B3LYP Computations of BaTiO 3 , CaTiO 3 , PbTiO 3 , SrTiO 3 , BaZrO 3 , CaZrO 3 , PbZrO 3 and SrZrO 3 Perovskites.

We performed B3PW and B3LYP computations for BaTiO 3 (BTO), CaTiO 3 (CTO), PbTiO 3 (PTO), SrTiO 3 (STO), BaZrO 3 (BZO), CaZrO 3 (CZO), PbZrO 3 (PZO) and SrZrO 3 (SZO) perovskite neutral (001) along with polar (011) as well as (111) surfaces. For the neutral AO- as well as BO 2 -terminated (001) surfaces, in most cases, all upper-layer atoms relax inwards, although the second-layer atoms shift outwards. On the (001) BO 2 -terminated surface, the second-layer metal atoms, as a rule, exhibit larger atomic relaxations than the second-layer O atoms. For most ABO 3 perovskites, the (001) surface rumpling s is bigger for the AO- than BO 2 -terminated surfaces. In contrast, the surface energies, for both (001) terminations, are practically identical. Conversely, different (011) surface terminations exhibit quite different surface energies for the O-terminated, A-terminated and BO-terminated surfaces. Our computed ABO 3 perovskite (111) surface energies are always significantly larger than the neutral (001) as well as polar (011) surface energies. Our computed ABO 3 perovskite bulk B-O chemical bond covalency increases near their neutral (001) and especially polar (011) surfaces.