Bonding at Oxide Surfaces

Concepts in chemical bonding when combined with physics-based energetic considerations can lead to a more complete understanding of the structure, stability, and reactivity of oxide surfaces. While this symbiosis has long been understood for bulk structures, chemical bonding considerations have historically been used less frequently for surfaces. In this chapter, we analyze the chemical bonding of published surface structures of SrTiO₃ and MgO using bond valence sum analysis. Bond valence theory compares favorably with complex quantum mechanical calculations in assessing surface structures and explains the experimentally observed surface structures in a readily comprehensible manner. Bond valence theory also helps explain discrepancies between DFT predicted surface stability and experimentally observed surface structures, accurately predicts the adsorption of foreign species onto surfaces, and can be used to predict changes in surface structures.