Self-Consistent Anharmonic Theory and Its Application to Ferroelectric Crystal

Abstract

The dielectric properties of barium titanate near the Curie temperature are studied using the variational principle method on a self-consistent anharmonic model. A trial Hamiltonian was devised using the terms of the anharmonic oscillator and asymmetric potential energy, which was adopted as the inter-atomic potential of the ferroelectric crystal. The temperature dependence of the dielectric property of barium titanate that was derived from this theory is in good agreement with the experimental result of the inter-atomic potential determined from first-principles ultrasoft pseudo potential calculations.

Keywords:

• Ferroelectric crystal
• barium titanate
• dielectric property
• variational principle method
• trial Hmiltonian
• anharmonic oscillator
• inter-atomic potential
• first-principles calculation
• free energy
• equilibrium condition