(color online) (a) Atomic-resolution image of the 180° domain structure in a PZT film close to the interface to the STO substrate, recorded along the [110] direction. The interface is marked by a horizontal dashed line. The domain wall is indicated by a yellow dotted line and the polarization is denoted by arrows. In the center of the lower half of the image, a dotted blue line surrounds an area, where in the center, the polarization direction makes an angle of 90° with the two large domains. The inset on the right-hand side shows a calculated image demonstrating the excellent match to the experimental image. (b) Map of the displacement vectors for the Zr/Ti atoms (arrows) from the center of the projected oxygen octahedra. The arrows represent electric dipole moment of unit cell. Note that the continuous rotation of the dipole directions from “down” (right) to “up” (left) closes the electric flux of the two 180° domains. (c) Magnification of upper part of (a) and (b), showing details of the domain wall facets where polarization charges depolarize the nearby unit cells and reduce the off-center displacements of the atoms in these unit cells.^[23]