FROZEN PHONON LMTO-CALCULATIONS FOR FERROELECTRIC PEROVSKITES

“Frozen” phonon calculations based on Density-Functional-Theory were performed for Ba TiO3, and SrTiO3 with a full potential version of the linear-muffin-tin-orbital method. It was demonstrated that the ferroelectric instability in perovskites is the result of a delicate balance between forces produced by bonding and nonbonding states. Calculations of the electric field gradient at finite temperatures and its comparison to recent NMR-measurements in the tetragonal phase of BaTiO3 allow conclusions about the displacement-displacement correlation function. © 1990, Taylor & Francis Group, LLC. All rights reserved.