Max-Planck-Inst. Festkoerperforsch., Stuttgart , 7000/80, Fed. Rep. Ger.

First principles "frozen phonon" calcns. based on the D.-Functional-Theory and a new Linear-Muffin-Tin-Orbital method were performed for BaTiO3 and SrTiO3. The ferroelec. lattice instability of BaTiO3 was reproduced by the calcn. without any adjustable parameter. Investigations of the relationship between electronic structure and crystal structure showed that the nonbonding Op states in the upper part of the cubic valence band become bonding in the tetragonal phase. They thus lower the energy of the low symmetry structure.
 

Ferroelectrics, 79 65-8, 1988.