PRINCIPLES OF COMPUTER-SIMULATION OF PHASE-TRANSITIONS AND DOMAIN PATTERN IN FERROIC SYSTEMS

The procedure to study the structural phase transition and the related domain pattern requires formulation of a model consistent with symmet ry of the high-and low-symmetry phases of the crystal. The harmonic mo des, including the soft mode, can be found from ab initio calculations , by the direct method, which uses the Hellmann-Feynman forces. Exampl es of ferroelastic systems which have been simulated, are referenced.