First-Principles Calculations for Ferroelectrics.
Final rept. 1 Nov 93-31 Dec 96,
COLLEGE OF WILLIAM AND MARY WILLIAMSBURG VA DEPT OF PHYSICS
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First-principles calculations for ferroelectrics reveal the existence of extended instabilities as a function of wavevector in KNbO3 and SrTiO3. The scope of the first-principles results is extended through the use of effective Hamiltonians, determined with no empirical or experimental input, using a database of first-principles calculations. Molecular dynamics simulations using these effective Hamiltonians then predict ferroelectric phase transition temperatures, phonon softening, and diffuse X-ray scattering behavior. These calculations also demonstrate for the first time the existence of preformed dynamic precursor chain-like structures in KNbO3 and BaTiO3, well above the ferroelectric transition temperatures.
- Inorganic Chemistry
- Ceramics, Refractories and Glass
- Electricity and Magnetism