Symmetry-allowed atomic displacements in a ferroelastic domain wall of rhombohedral BaTiO3

Displacements of atoms in a domain wall are confined by local symmetry which can be deduced from the layer group describing the symmetry of the wall. This symmetry confinement specifies completely or partially the direction of atomic displacement at each site and provides relations between displacements at different sites. The approach has been applied to mechanically compatible ferroelastic 71° charged domain wall with central plane at centred oxygen atoms in the rhombohedral phase of BaTiO₃.