Molecular dynamics simulation of KNbO3: Relaxational dynamics and precursor domains

M. SEPLIARSKY; M. G. STACHIOTTI; R. L. MIGONI

FERROELECTRICS

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 1996 vol. 183 p. 105 - 114

0015-0193

The dynamics of the ferroelectric phase transition in KNbO3 is studied by means of a molecular dynamics simulation in the framework of the nonlinear oxygen polarizability model. The validity of the shell model potential to describe the sequence of phase transitions in KNbO3 is tested by comparing the underlying static potential for the ferroelectric distortions with recent ab-initio calculations. The specific goal is to study the crossover from displacive to order-disorder behavior near the cubic-tetragonal phase transition. The appearance of a central peak in the dynamical structure factor and the onset of relaxation in the local ionic dynamics are analyzed.