LINEARIZED AUGMENTED PLANE-WAVE TOTAL ENERGY CALCULATIONS FOR FERROELECTRIC BATIO3

The ferroelectric instability in BaTiOa has been studied using the full potential Linearized Augmented Plane Wave (LAPW) method. The energy wells for the soft mode distortion are deeper for rhombohedral [111] displacements relative to tetragonal [001] displacements, but both are relatively shallow and comparable to the transition temperature. The tetragonal lattice strain greatly reduces the total energy for tetragonal BaTi03, but the rhombohedral strain has little effect. These calculations show that the ferroelectric instability in BaTi03 can be understood in terms of a perfect, infinite crystal with periodic boundary conditions. © 1990, Taylor & Francis Group, LLC. All rights reserved.