Abstract
We established a new ab initio structure optimization technique of determining the valley line on a total-energy surface accurately for the zone-center distortions of ferroelectric perovskite oxides, and applied this technique to the analysis of barium titanate (BaTiO3), lead titanate (PbTiO3), and lead zirconate (PbZrO3). The proposed technique is an improvement over King-Smith and Vanderbilt's scheme [Phys. Rev. B 49 (1994) 5828] of evaluating total energy as a function of the amplitude of atomic displacements. The results of numerical calculations show that total energy can be expressed as a fourth-order function of the amplitude of atomic displacements in BaTiO3 but not in PbTiO3 and PbZrO 3. These results will provide some hints about the reason Pb(Zr xTi1-x)O3(PZT) has a large piezoelectric response. These results are due to the fact that our structure optimization technique automatically takes account of the higher-order coupling between atomic displacements and strains, and not only the atomic displacements of the ΓO15 soft mode but also that of the hard modes.
Original language | English |
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Pages (from-to) | 6785-6792 |
Number of pages | 8 |
Journal | Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers |
Volume | 43 |
Issue number | 9 B |
DOIs | |
Publication status | Published - 2004 Sept |
Externally published | Yes |
Keywords
- First-principles calculation
- Lagrange multiplier
- Lead-free
- Potential surface
- Valley line
ASJC Scopus subject areas
- Engineering(all)
- Physics and Astronomy(all)