First-Principle Studies on Elastic Properties and Spontaneous Polarizations of PbTiO3.

The elastic properties of the tetragonal phase of PbTiO3 were investigated using the full-potential linearized argumented plane wave (FLAPW) method. The geometric optimization calculations were performed against the lattice deformations. It is shown that the elastic properties including the sublattice relaxations can be well described by the simple Hook's law. The value of the spontaneous polarization using Berry's phase approach based on the optimized geometry fairly reproduced the experimental value.