Quantum paraelectricity in the self-consistent phonon approximation

Abstract

The dielectric susceptibility of potassium tantalate has been computed in the framework of an approach, earlier proposed by Vaks [V.G. Vaks. Vvedenie v mikroskopicheskuiu teoriju segnetoelektrikov. Moskva, Nauka 1973 (in Russian)]. This theory deals with a perturbation series for the temperature Green functions rather than with the mean field approach. The small parameter is the anharmonicity potential. The phonon spectrum, required for the computation, was taken from a recent study by Farhi et. al. [Europ. Phys. J. B (in print)]. Qualitative agreement has been obtained between theory and experiment.

Key Words:

• quantum effects
• ferroelectricity
• computation