Year: 1997
Type: article
Abstract: An effective Hamiltonian for the ferroelectric transition in ${\mathrm{PbTiO}}_{3}$ is constructed from ab initio pseudopotential local-density-functional total-energy and linear-response calculations through the use of a localized, symmetrized basis set of ``lattice Wannier functions.'' Explicit parametrization of the polar lattice Wannier functions is used for subspace projection, addressing the issues of LO-TO splitting and coupling to the complementary subspace. In contrast with ferroelectric ${\mathrm{BaTiO}}_{3}$ and ${\mathrm{KNbO}}_{3}$, we find significant involvement of the Pb atom in the lattice instability. Monte Carlo simulations for this Hamiltonian show a first-order cubic-tetragonal transition at 660 K. The resulting temperature dependence of spontaneous polarization, c/a ratio, and unit-cell volume near the transition are in good agreement with experiment. Comparison of Monte Carlo results with mean-field theory analysis shows that both strain and fluctuations are necessary to produce the first-order character of this transition.
Authors: U. V. Waghmare, K. M. Rabe
Institution: Yale University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2171752110