COMPUTER-SIMULATION OF DOMAIN FORMATION IN THE ORDER-DISORDER PHASE-TRANSITION OF THE KSCN MODEL

The tetragonal-orthorhombic improper ferroeleastic phase transition an d domain formation of the order-disorder KSCN model is studied by mole cular-dynamics simulation. A two-dimensional model of either 105 x 105 or 49 x 49 unit cells represents a layer of this crystal. The simulat ion determines the orientational and strain order parameters and trans ition temperature. The mean-field theory gives excellent qualitative a greement of the calculated and simulated phase transition temperature. On quenching from the disorder phase and subsequent annealing, a twee d texture is obtained, which later evolves to a stripe phase with well oriented ferroelastic domain walls and arbitrarily oriented antiphase boundaries.