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An extensive set of DFT calculations on LaMnO 3 slabs has been generated and used as a basis to identify the most probable reaction mechanism for oxygen incorporation into (La, Sr)MnO 3-δ cathode materials. MnO 2 [001] is found to be the most stable surface termination under fuel cell operation conditions (high temperature, high pO 2 , cubic unit cell). Chemisorption leading to the formation of O 2 -, O 2 2-, and O -atop Mn is exothermic, but due to the negative adsorption entropy and electrostatic repulsion the levels of coverage of molecular oxygen adsorbates are low (in the few percent range). Under typical solid oxide fuel cell conditions, a mechanism in which the encounter of O -with a surface oxygen vacancy at the surface is rate-determining exhibits the fastest rate. The variation of the reaction rate and preferred mechanism(s) with adsorbate and point defect concentrations is discussed.

We present and discuss the results of calculations of SrTiO 3 ͑100͒ surface relaxation and rumpling with two different terminations ͑SrO and TiO 2 ͒. These are based on ab initio Hartree-Fock method with electron correlation corrections and density functional theory calculations with different exchange-correlation functionals, including hybrid exchange techniques. Both approaches use the localized Gaussian-type basis set. All methods agree well on surface energies and on atomic displacements, as well as on considerable increase of covalency effects nearby the surface. More detailed experiments on surface rumpling and relaxation are necessary for further testing theoretical predictions.