The (2 x 2) reconstructions on the SrTiO3 (001) surface: A combined scanning tunneling microscopy and density functional theory study

Scanning tunneling microscopy study showed that the (2 x 2) reconstruction on the (001) surface of SrTiO3 should have a surface structure with a 4-fold symmetry. The previously proposed solution for the (2 x 2) reconstruction with the p2gm symmetry only has a 2-fold symmetry. In this study density functional theory study was carried out to propose a possible surface structure with the p4mm surface symmetry which matches the scanning tunneling microscopy images and suggests that two different (2 x 2) surface structures exist. The formation of the (2 x 2) reconstruction with the p4mm symmetry may be due to the kinetics as it has slightly higher surface energy than the one with the p2gm symmetry. (C) 2011 Elsevier B.V. All rights reserved.