Surface relaxation of the (110) face of rutile SnO2

Surface relaxation of the stoichiometric and reduced SnO2 (110) surfaces is studied with first-principles calculations. Calculations are carried out w ith two different self-consistent ab initio LDA methods, which lead to simi lar results. The most prominent feature in the relaxation is that the surfa ce layer oxygens of the reduced surface move outwards about 0.4 Angstrom wi th respect to the surface tin atoms. The stoichiometric (oxidized) surface is stabilized by the "bridging" oxygen atoms, and therefore, relaxes less. The valence band density-of-states is similar at both surfaces, except that removing bridging oxygens leaves behind electrons that occupy gap states f ormed at the reduced tin atoms. (C) 1999 Elsevier Science B.V. All rights r eserved.