DYNAMICAL STUDY OF PHONONS IN PBTIO3

A lattice dynamical formalism, using a rigid ion model, was applied to the crystal of PbTiO//3 in the tetragonal phase. The model includes long-range Coulomb forces and short-range axially symmetric forces. The radial part of the short-range force constants was assumed to be of Born-Meyer type. The parameters of the model were determined through a least squares analysis of zone center and a few zone boundary phonons. Dispersion curves for left bracket 100 right bracket and left bracket 001 right bracket directions are presented.