First‐principles study of the (001) surface of cubic PbTiO3

Abstract

AbstractWe present first‐principles calculations on the (001) surfaces of cubic PbTiO3 with PbO and TiO2 terminations. The cleavage energy, surface energy, surface grand potential, surface relaxation and surface electronic structure have been investigated by using the projector‐augmented wave method under generalized gradient approximation (GGA). The results show that surface energy of a TiO2‐terminated surface is a little lower than that of a PbO‐terminated one, thus allowing both terminations to coexist. The PbO‐termination is stable in O‐ and Pb‐rich environments, while on the contrary, the TiO2‐termination is stable in O‐ and Pb‐poor conditions. In addition, the surface rumpling S of a PbO‐terminated surface is slightly larger than that of a TiO2‐terminated one. The relaxations dominantly take place on the outermost three layers, and an oscillatory (− + −) damping (|Δd12 | > | Δd23 | > | Δd34|) relaxation phenomenon appears for both terminations. The band gaps of both PbO‐ and TiO2‐terminations are slightly lower than that of the bulk. Moreover, the DOS curves of each layer show that for the TiO2‐termination, the top of the valence band of the first and third TiO2 layers moves toward Fermi level. Copyright © 2008 John Wiley & Sons, Ltd.