Energetics and structure of stoichiometric SnO2 surfaces studied by first-principles calculations

First-principles calculations based on density-functional theory, ultrasoft pseudopotentials and plane-wave basis sets are used to investigate the ene rgetics and the relaxed ionic positions of several low-index stoichiometric SnO2 surfaces. We find that, in order of increasing energy, the surfaces f orm the sequence (110)<(100)<(101)<(001). The prediction that (110) is the most stable surface agrees with earlier experimental and theoretical indica tions, but the relative stability found for (100) and (101) disagrees with earlier shell-model predictions. Ionic relaxations at all Four surfaces are moderate, with no displacement exceeding ca. 0.3 Angstrom. Comparisons wit h theoretical and experimental results for the ionic relaxations at the sam e surfaces of TiO2 are presented. (C) 2000 Elsevier Science B.V. All rights reserved.