First-Principles Calculations for Ferroelectrics.

Abstract

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.

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Document Details

Document Type
Technical Report
Publication Date
May 01, 1997
Accession Number
ADA324581

Entities

People

  • Henry Krakauer

Organizations

  • College of William & Mary

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Dielectric Permittivity
  • Dynamics
  • First Principles Calculations
  • Lattice Dynamics
  • Materials
  • Materials Science
  • Molecular Dynamics
  • Phase Transformations
  • Physics
  • Precursors
  • Scattering
  • Simulations
  • Transition Temperature
  • Transitions
  • X Ray Scattering
  • X Rays

Fields of Study

  • Physics

Readers

  • Computational Modeling and Simulation
  • Materials Science and Engineering.
  • Quantum spin resonance or Electron Paramagnetic Resonance spectroscopy.