Structure and energetics of 180° domain walls in PbTiO3 by density functional theory

Density functional theory at the level of the local density approximation with the projector augmented wave method is used to determine the structure of 180 degrees domain walls in tetragonal ferroelectric PbTiO3. In agreement with previous studies, it is found that PbO-centered {100} walls have lower energies than TiO2-centered {100} walls, leading to a Peierls potential barrier for wall motion along < 010 > of similar to 36 mJ m(-2). In addition to the Ising-like polarization along the tetragonal axis, it is found that near the domain wall, there is a small polarization in the wall-normal direction away from the domain wall. These Neel-like contributions to the domain wall are analyzed in terms of the Landau-Ginzburg-Devonshire phenomenological theory for ferroelectrics. Similar characteristics are found for {110} domain walls, where OO-centered walls are energetically more favorable than the PbTiO-centered walls.